3.75 GB and 6GB Offline files problem - Sick of re-initializing

Laptops are XP Pro, running off Server 2003 Standard.  I have a couple of users who continually have problems with their offline folders being able to sync, they receive the parameter incorrect message and I have to re-initialize their folders.  There are numerous other offline folder uses who are not having any issues at all like this.  The two users having this problems have offlines folder sizes of 3.75GB and 6GB respectively.  I am not sure what is a reasonable offline folder size but I am guessing this is too much and that is possiblt what is causing this problem to keep coming up.  Having to reinitialize and re-sync is really becoming a problem, both with these two not liking the fact they keep getting an error, and myself having to take the time to run thru the process.

Both users are top executives and want to keep all of their data and existing folder structure in their offline folders, so it is not as easy as just cleaning up their folders.

What I am looking for is an alternate solution or recommendation to my current setup, to synchronize new documents and files without running into this same problem that we are having.  If anyone else using offline folders this large without this issue I would like to hear from you.