Thank you again for your assistance. I ran EtreCheck as you suggested. I ran the suggested Malwarebytes ANTI-MALWARE for Mac, too, but it only removed a couple of adware apps which I know are not the problem. Otherwise, this is the result:
EtreCheck version: 2.7.2 (232)
Report generated 2016-01-16 10:43:03
Download EtreCheck from http://etrecheck.com
Runtime 2:33
Performance: Excellent
Click the [Support] links for help with non-Apple products.
Click the [Details] links for more information about that line.
Click the [Scan for adware] links for help removing adware.
Problem: Other problem
Description:
Co-workers of mine seem to have access to everything I do and look at on my iMac.
Hardware Information: ⓘ
iMac (27-inch, Mid 2011)
[Technical Specifications] - [User Guide] - [Warranty & Service]
iMac - model: iMac12,2
1 2.7 GHz Intel Core i5 CPU: 4-core
8 GB RAM Upgradeable - [Instructions]
BANK 0/DIMM0
4 GB DDR3 1333 MHz ok
BANK 1/DIMM0
4 GB DDR3 1333 MHz ok
BANK 0/DIMM1
Empty
BANK 1/DIMM1
Empty
Bluetooth: Old - Handoff/Airdrop2 not supported
Wireless: en1: 802.11 a/b/g/n
Video Information: ⓘ
AMD Radeon HD 6770M - VRAM: 512 MB
iMac 2560 x 1440
System Software: ⓘ
OS X El Capitan 10.11.2 (15C50) - Time since boot: about 3 days
Disk Information: ⓘ
ST31000528AS disk0 : (1 TB) (Rotational)
EFI (disk0s1) <not mounted> : 210 MB
Macintosh HD (disk0s2) / : 999.35 GB (830.59 GB free)
Recovery HD (disk0s3) <not mounted> [Recovery]: 650 MB
HL-DT-STDVDRW GA32N ()
USB Information: ⓘ
Apple Inc. FaceTime HD Camera (Built-in)
Mitsumi Electric Apple Optical USB Mouse
Apple Inc. BRCM2046 Hub
Apple Inc. Bluetooth USB Host Controller
Logitech Logitech USB Headset
LaCie P'9221 Mobile Drive 500.11 GB
EFI (disk1s1) <not mounted> : 210 MB
Time Machine (disk1s2) /Volumes/Time Machine : 499.76 GB (91.26 GB free)
Apple Computer, Inc. IR Receiver
Apple Card Reader
Thunderbolt Information: ⓘ
Apple Inc. thunderbolt_bus
Gatekeeper: ⓘ
Mac App Store and identified developers
Adware: ⓘ
Adware infection possible. [Scan for adware]
Kernel Extensions: ⓘ
/Library/Application Support/MacKeeper/AntiVirus.app
[not loaded] com.zeobit.kext.AVKauth (2.3.2 - SDK 10.7) [Support]
[not loaded] com.zeobit.kext.Firewall (2.3.2 - SDK 10.7) [Support]
/System/Library/Extensions
[not loaded] com.Cycling74.driver.Soundflower (1.5.1) [Support]
Launch Agents: ⓘ
[loaded] com.google.keystone.agent.plist ✓ [Support]
[running] com.machangout.glims.agent.plist [Support]
[running] com.opendns.osx.DNSCryptMenuBar.plist [Support]
[loaded] com.teamviewer.teamviewer.plist ✓ [Support]
[loaded] com.teamviewer.teamviewer_desktop.plist ✓ [Support]
[running] net.culater.SIMBL.Agent.plist ✓ [Support]
Launch Daemons: ⓘ
[loaded] com.adobe.fpsaud.plist ✓ [Support]
[running] com.anonymizer.deltavpn.DeltaVPNInstaller.plist [Support]
[loaded] com.anonymizer.deltavpn.DeltaVPNOpenVPNHelper.plist [Support]
[running] com.anonymizer.deltavpn.GreenlightInterrogator.plist [Support]
[running] com.anonymizer.deltavpn.L2TPConfigurator.plist [Support]
[loaded] com.anonymizer.deltavpn.OpenVPN.plist [Support]
[loaded] com.google.keystone.daemon.plist ✓ [Support]
[running] com.machangout.glims.loader.plist [Support]
[running] com.opendns.osx.DNSCryptConfigUpdater.plist [Support]
[loaded] com.teamviewer.Helper.plist ✓ [Support]
[loaded] com.teamviewer.teamviewer_service.plist ✓ [Support]
[running] com.zeobit.MacKeeper.AntiVirus.plist [Support]
[failed] net.tunnelblick.tunnelblick.startup.vpnbook--us1--udp53.plist [Support]
[loaded] net.tunnelblick.tunnelblick.tunnelblickd.plist [Support]
User Launch Agents: ⓘ
[failed] com.adobe.ARM.[...].plist ✓ [Support]
[failed] com.jdibackup.ZipCloud.autostart.plist [Support] [Details]
[failed] com.jdibackup.ZipCloud.notify.plist [Support] [Details]
[running] com.zeobit.MacKeeper.Helper.plist [Support]
[failed] net.tunnelblick.tunnelblick.LaunchAtLogin.plist [Support]
[loaded] uk.co.markallan.clamxav.freshclam.plist ✓ [Support]
User Login Items: ⓘ
smcFanControl Application (~/Downloads/smcfancontrol_2_4/smcFanControl.app)
iTunesHelper Application (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)
PandoCalendar Application (/Applications/PandoCalendar.app)
Canon IJ Network Scanner Selector EX Application Hidden (/Applications/Canon Utilities/IJ Network Scanner Selector EX/Canon IJ Network Scanner Selector EX.app)
Typinator Application (/Applications/Typinator.app)
Mail Application (/Applications/Mail.app)
Google Drive Application (/Applications/Google Drive.app)
Skype Application Hidden (/Applications/Skype.app)
iLauncherHelper UNKNOWN Hidden (missing value)
OpenDNS Updater Application Hidden (/Applications/OpenDNS Updater.app)
Stickies Application (/Applications/Stickies.app)
Dave.pastor Pastor Document (~/Documents/Pastor 1.8.2/Dave.pastor)
Other Apps: ⓘ
[running] com.apple.xpc.launchd.oneshot.0x1000000b.EtreCheck
[running] com.eidac.smcFanControl2.13792
[running] com.google.GoogleDrive.8992
[running] com.macility.typinator2.68192
[running] com.opendns.OpenDNS_Updater.84512
[running] com.opendns.osx.DNSCryptProxy
[running] com.pandasystems.pandocalendar.84832
[running] com.skype.skype.146272
[loaded] com.vimov.weatherhd.mac.menulauncher
[running] jp.co.canon.cijscannerregister.16992
[running] jp.co.canon.ij.CNSSelectorAgent.93792
[running] net.mehlau.pastor.63392
Internet Plug-ins: ⓘ
Flip4Mac WMV Plugin: Version: 3.2.0.16 - SDK 10.8 [Support]
FlashPlayer-10.6: Version: 20.0.0.267 - SDK 10.6 [Support]
QuickTime Plugin: Version: 7.7.3
Flash Player: Version: 20.0.0.267 - SDK 10.6 [Support]
EPPEX Plugin: Version: 3.0.5.0 [Support]
Default Browser: Version: 601 - SDK 10.11
Silverlight: Version: 5.1.40416.0 - SDK 10.6 [Support]
User internet Plug-ins: ⓘ
Google Earth Web Plug-in: Version: 7.0 [Support]
Safari Extensions: ⓘ
AdBlock
TinEye
Cookie Stumbler
InvisibleHand
StartPage HTTPS
3rd Party Preference Panes: ⓘ
DNSCrypt [Support]
Flash Player [Support]
Flip4Mac WMV [Support]
Time Machine: ⓘ
Skip System Files: NO
Mobile backups: OFF
Auto backup: YES
Volumes being backed up:
Macintosh HD: Disk size: 999.35 GB Disk used: 168.76 GB
Destinations:
Time Machine [Local]
Total size: 499.76 GB
Total number of backups: 165
Oldest backup: 7/29/13, 6:10 AM
Last backup: 1/16/16, 9:47 AM
Size of backup disk: Too small
Backup size 499.76 GB < (Disk used 168.76 GB X 3)
Top Processes by CPU: ⓘ
2% fontd
2% WindowServer
1% kernel_task
0% Dock
0% Google Drive
Top Processes by Memory: ⓘ
739 MB kernel_task
467 MB softwareupdated
287 MB com.apple.WebKit.WebContent(3)
262 MB mds_stores
229 MB Skype
Virtual Memory Information: ⓘ
2.22 GB Free RAM
5.78 GB Used RAM (2.78 GB Cached)
0 B Swap Used