Yikes, this is a lot of posts... reviewing:
zig2101: try what chaiusa did and delete the Unihan database (if you've installed it) - a few other people have said by e-mail that they're also encountering crashes related to using Unihan, and it could easily cause the flashcard problem as well.
koreth (first few) - did you install your product keyfile the first time? The handwriting recognition files are part of that now, but it shouldn't be possible to unlock PlecoDict without installing the keyfile, so I'm surprised that the software was still unlocked.
koreth (next bug one) - that fatal exception crash may have also been related to Unihan (the Treo isn't always good about reporting error messages), try deleting that and see if it helps matters. Also, how much free space do you have on your Treo? If you've using a lot of custom dictionaries then a couple of MB would probably be best.
And nitpick bug reports are bug reports all the same, thanks very much for pointing that one out. (especially important on devices like the Treo which switch into number-shift mode for numeric fields)
goulniky - did you install the Unihan database? From what I've heard so far this seems like it could easily be Unihan-related too; if the dictionary can't find a match in the ABC then it'll scan through all of the other installed dictionaries, including Unihan.
Ross - this is related to your problem in the other topic, install the "Large High-Resolution Font" and this stuff should work. We really need to fix this in the manual...
haraldalbrecht - I second your recommendation to buy an external SD reader, they're dirt-cheap (< $10) and much more reliable than a HotSync. Of course if Palm simply did what Microsoft and Sony did and built drive-mounting functionality into every handheld we wouldn't have this problem...
Judy - I'll wait to see how the card-mounting turns out before weighing in in detail, but in general I think the best thing to do at this point would be to reformat the SD card, hard reset your Tungsten, delete the Backup, Install, CardInst, and QuickInstall subfolders in your Palm Desktop user folder, and start again from scratch. You might also consider updating to the latest version of Palm Desktop - on my system at least, installing a data file to an SD card brings up a helpful little progress meter that shows you the exact % transferred as it goes along.