Hi Joe, I suspect the external is disconnecting itself or such.
In Finder's Menu, select Go menu>Go to Folder, and go to "/volumes". (no quotes)
Volumes is where an alias to your hard drive ("/" at boot) is placed at startup, and where all the "mount points" for auxiliary drives are created for you to access them. This folder is normally hidden from view.
Drives with an extra 1 on the end have a side-effect of mounting a drive with the same name as the system already think exists. Try trashing the duplicates with a 1 or 2 if there are no real files in them, and reboot.
If it does contain data...
Thanks for your quick response, BDAqua - OK, here's new information!
After shutting down, powering down all the external drives and rebooting it all, the system drive came back with all of the supposedly "added data" mysteriously gone! The boot drive had been showing "zero space available" but after reboot it showed 10 gigs of available space (which is the expected amount.)
So for some reason the OS was reporting that the system drive was full (I got the warning message saying there is almost no space left on the boot drive) even though in reality it was not full.
Do you have any idea what might cause this glitch in reporting? As I say, the only thing I did before this problem came up was to turn on Time Machine. I don't want to turn Time Machine back on until I know what's happening.
Oh, BTW, when I looked at the root "/volumes" directory, there were no duplicates of my connected drives, but there were names of thumb drives I use (which are not connected) and also a old drive name for which the drive no longer exists. There were no files in their directories, so I trashed them. This may explain whay I sometimes had trouble getting thumb drives to unmount.
Oh boy Joe, what Apple doesn't tell you is that 10 GB of free disk space is not enough AND isn't free for your use, and in my experience 10.5.8 will be sluggish with less than 30 GB free, higher OS versions needing even more.
Open Activity Monitor in Applications>Utilities, select All Processes & sort on CPU%, any indications there?
How much RAM & free space do you have also, click on the Memory & Disk Usage Tabs.
In the Memory tab, are there a lot of Pageouts?
See if you can clear off a few GBs.
How much free space is on the HD, where has all the space gone?
OmniDiskSweeper is likely the easiest/best, and is now free...
That should make it increadably slow with so little green/free memory.
You need more RAM & more free space on the drive.
So we know more about it...
At the Apple Icon at top left>About this Mac, then click on More Info, then click on Hardware> and report this upto but not including the Serial#...
Model Name: iMac
Model Identifier: iMac7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 6 GB
Bus Speed: 800 MHz
Boot ROM Version: IM71.007A.B03
SMC Version (system): 1.21f4