I am currently trying to migrate my data in Palm Desktop 4 (that's right, the one that came with the Pilot m500...) to a new Blackberry using the Desktop Manager's "Device Switch Wizard." Although it seems to be working at first, it completely stops (and becomes "Not Responding") after importing exactly 2971 records from the Calendar - which happens to be the first thing it pulls out. Closing the instance of Palm Desktop that the Wizard opens (both before and after it freezes) and waiting for over 15 minutes both do no good. I'm not sure whether or not it is a RAM issue, as there is a RAM meter on my Vista Sidebar and it stayed almost constant at 38% out of the almost 3GB of RAM I have.
In all probability, there is something wrong with the 2972nd record.
It may be corrupt. It might contain illegal characters. A critical field in it might be empty. Recurring events without an end date could cause problems.
If you can identify that record, delete it and try again.
If you can't identify that record, then I'd suggest turning on Advanced Logging in Desktop Manager and then run a synch. After it fails, check the log and at the bottom, you will find the last successful record. The subsequent one should be the problematic record.
Alternatively, Palm Desktop should have the ability to export records into something you can view in a spreadsheet. Export them and then find that record. Inspect it to confirm that you're using lower ASCII (no control characters), and also for the other things I mentioned in the second paragraph.
(I know nothing about Blackberry, I use Palm Treo and Centro.) However, this sounds like a generic issue with corruption with your Palm database. If you even just suspect corruption, download the outstandingly helpful dbFixIt from Pimlico Software. dbFixIt runs on the Palm device, not on the Desktop itself.
I tried it and it finds and fixes lots of corruptions (often related to BLOBs in Datebook, at least in my personal experience).
FREE shareware program with unlimited free trial to run in detection mode; only need to purchase for $12.95 to use it in repair mode. So it's a risk-free proposition. And it's well worth it. Very widely recommended by armies of grateful Palm users.
I can personally vouch from painful experience for every single word of what Pimlico state: "Corrupt databases can cause all kinds of problems from crashing applications, hanging or crashing conduits, or causing unexpected errors ..."
By the way, Palm Desktop 4 is pretty ancient, you should also try Palm Desktop 6.2 (final, not the beta) for Vista which is ok.