I am unable to open drawing files previously created from my main assembly. These drawings have previously been opened with no problem. I have a similar situation when trying to create new drawings from the same main assembly, Inventor locks up and the cpu goes to 100%. The main assembly can be opened no problem and all of the representations are functional there are no errors showing up on the assembly all appears to be resolved. I have loaded SP3 and that has not helped.

Can anyone offer advice here, I am becoming rather desperate?