Welcome to Apple Discussions.
Reinstalling the Palm Desktop was a really bad idea. Although you believe it changed nothing, it actually changed everything. And, it could not possibly have corrected the original issue, which almost certainly does not involve the HotSync Manager or Transport Monitor, and could not have involved the remained of the Palm package at all.
Palm device synchronization using iSync and the iSync Palm Conduit will not work until you have address the issues which reinstalling it created, and the original issue which prevented the execution of a synchronization event.
To correct this, you should first remove your Palm device from iSync.
Then, apply this software package to update Mac OS X 10.4.9 for your PowerPC-based Macintosh:
http://www.apple.com/support/downloads/macosx1049comboupdateppc.html
You must use this package to perform the update, as neither the smaller delta updater of the Software Update mechanism will perform the necessary changes to your configuration.
Once you've done that, you should launch iSync 2.4 and use the Enable Palm OS Syncing… option under the Devices menu to once again add your Treo to iSync. It's probably better to initiate this process via USB, though if you elect to use Bluetooth instead, be sure that you pair your smartphone to your computer prior to attempting to add it to iSync.
If you cannot add it as a device, stop and post the error messages you see rather than trying to address them. This process should be straightforward and simple but it often is not, and proceeding without understanding the impact of what you are doing may force you to start this procedure all over again.