Crash on update to 2.5.1

I did a search on the forum and didn't find anything along the lines of what I'm experiencing, but I apologize in advance if this has already been answered...

I just recently upgraded to version 2.5.1 from version 2.4.3. When I try loading this version, I get a "Pidgin has stopped working" error message. When I view the problem details, I get this:
Problem signature:
Problem Event Name: APPCRASH
Application Name: pidgin-portable.exe
Application Version: 2.5.1.0
Application Timestamp: 48ba1264
Fault Module Name: libmsn.dll
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 48ba1264
Exception Code: c0000005
Exception Offset: 00010cb0
OS Version: 6.0.6001.2.1.0.256.1
Locale ID: 1033
Additional Information 1: e479
Additional Information 2: 616acab68c46072bc8855040a524f929
Additional Information 3: 226f
Additional Information 4: 62799c54f40ce33e31a343df8f0f3603
I also saw a message that said "An unhandled win32 exception occurred in pidgin-portable.exe [3652]. This message was from my laptop running Windows Vista with Service Pack 1.

I also tried this on my Windows 2000 SP4 machine, and also got an error message. Does this mean I have a corrupt profile on my thumb drive? I'm not sure what to try next. Any suggestions would be much appreciated.

Thanks in advance!