When attempting to save a project back from Microsoft Project (MSP) to Clarity PPM, a target error is generated that includes the following: 

Beginning of message: Target: System Object ForwardC?TolinvokeMember (System String...

Error referenced: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

This issue can happen if the MSP file is saved as an earlier version of MSP such as MSP2007 and not the default of "Project (*.mpp)". 

To check if the above is the cause and correct it,:

1. Save the project locally on the machine by doing a File ->Save As
2. Make sure the Save as Type is set to Project. If not, select Project, and save the project locally.
3. Then, you should be able to save the project back to Clarity without issue. 

To prevent the issue from reoccurring, make sure that the following is set in MSP:

1. Go to File->Options->Save in MSP
2. Check if "Save Files in this format" is defaulting to MSP2007 (or something else that is not Project), and if yes, change it to "Project (*.mpp)" to keep this issue from happening when users save projects locally. 
3. Click OK to save the change

Reference MSP Integration known issues - master KB