Deleted the /Library/Caches files

When you delete the Cache folder you must restart. Otherwise the cache files are not rebuilt.

I believe whatever problem you are having it's unrelated to the cache folders. I'm afraid your "friend" isn't a reliable troubleshooter.

There are no viruses affecting Macs. From what you've described I would say you have some serious problems on the hard drive. They may be fixable but if there are individual files corrupted then that's another story. You can start by trying the following:

Repairing the Hard Drive and Permissions

Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now shutdown the computer for a couple of minutes and then restart normally.

If DU reports errors it cannot fix, then you will need Disk Warrior (4.0 for Tiger) and/or TechTool Pro (4.5.2 for Tiger) to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.

If the above doesn't help then see the following (this is all pretty much pre-Tiger but may be helpful):

Originally contributed by MacJack:

1. Navigate to YourHome/Library/Fonts - drag this folder to the desktop.

• Restart and test your applications.
• If they work start adding the fonts back few at a time.

(Likely suspects are TimesRO & Helvetica Fractions, also if you do not use Classic you can trash the classic fonts.)

2. Check Preferences Thoroughly:

• Go to Users/Your_Name/Library/Preferences and trash the files:

- com.apple.ATS.plist
- com.apple.BezelServices.plist

Restart. If this did not help, go to Users/Your_Name/Library and drag the folder
Preferences to the desktop. Restart and see if this solved the problem

• Navigate to YourHome/Library/Preferences drag this folder to the desktop.
• Restart and test your applications.
• If this works, save the old preferences folder somewhere else or on disk, name it
"old prefs."

** Note: A very important file is the "com.apple.Mail.plist" preference file located in the Preferences folder which contains all email account settings and general mail preferences (hold this one and replace if your problem is not with Mail).

You'll have to go through some of your System Preferences and apps to set the preferences back to how you like them. (Or if you have the time and inclination, "cherry pick" through until you find the problem one or two.)

3. Check Permissions Inside Home Folder

• Navigate to yourhome/library.
• Get Info (Command + i) on the "Applications Support" folder.
• Open the "Ownership & permissions" disclosure triangle.
• Make sure you are the owner, with "read and write" access.
• Click on "apply to all"
• If this is correct, open the "Applications Support" folder and do the same procedure
(Command+I) for the folder names of the applications with which you are having trouble.

Note:

The reason to check this is because repairing permissions with Disk Utility doesn't touch permissions inside your home folder.

If this doesn't help then the next step is to determine if you have a problem with corrupted files in your Home folder. To test his you need to open the Accounts preferences (System Preferences) and create a new user account. Log out of your normal account and log into the new account. Do you still have problems with your various applications that were quitting unexpectedly?

Before meddling with /Library or anything else at the system level, first determine if this is a system-wide problem or a problem specific to your user account. Do you get the same problems with the apps if you run them in a different user account?