I started running into this error when attempting to create a site collection in a different language. I would browse to Central Administration and choose a different language and immediately receive "there was an error in the callback". If I continued on and ignored the error I would receive "Exception occurred. (Exception from HRESULT: 0x80020009 (DISP_E_EXCEPTION))" after clicking Create. After lots of time wasted scouring the net I found a random post that said they ran into this error when they had a badly formatted webtempXXX.xml file.
I had missed a closing quote around my hidden parameter (looked like this: HIDDEN="TRUE). I fixed it, did an iisreset, and it fixed the problem.