I had the same error message. In my case, however, we tried to upgrade to the latest version of GPS Analyst and GPScorrect. GPS Analyst (2.40) would not work with ArcMap 10. We could not enable the extension because it did not appear in the extension list. Therefore we downgraded to an earlier version of GPS Analyst. At that point, it worked with ArcMap. I checked out data, collected gps points, and when I tried to check the data back in, I got that error message. As it turns out, I neglected to downgrade the GPScorrect software on my mobile device. Once I did that, my check out/check in proceedures worked fine.
I have no explanation as to why the latest version of GPS Analyst did not work with ArcGIS 10 (sp 5).
So...in a nutshell, our software versions were incompatible.