Hi, all! Bet you thought I'd given up. HAH!
I did, however, reinstall VL Soho 5.8. This was after investigating other possible causes (cheap optical mouse) and resetting KDE with Thunderbird and Firefox as default clients. This last, by the way, seemed to improve things, but not enough. I did a couple things different on this install:
1) Created a separate home partition, and
2) Used the open source Nvidia driver instead of the proprietary.
After a week of sheer hell (won't bore you with the details) of getting my Windows partitions to boot properly, I'm back and posting from VL! One strange thing, though. In my first install, I couldn't get Lilo to write to the mbr and I had to use Grub. This time, Grub wouldn't work but Lilo installed just fine??? The Grub problem probably has more to do with my screwed up Windows bootloader, but I wonder why Lilo wouldn't work the first time.
Anyway, I removed Seamonkey with Gslapt and modified the profiles.ini for both Thunderbird and Firefox to use the profiles stored on my Win 98 partition, and set the default clients in KDE to Thunderbird and Firefox. . Everything seems to work so far, I've been surfing happily without a crash. All 3 OS's see the same emails, bookmarks, and settings.
Just one more app to go - Kbarcode. This is a killer app for me, gotta have it. If it doesn't screw up Firefox, I will BE Vector Linux!
I'll let you know how it goes...