Well I can't say that I have experienced this particular problem myself. At least for quiet a number of years and certainly not since installing the final service pack for media studio 8.0. So the only thing I would be able to add would be to inquire as to whether or not you have installed the last service pack update for that program which would be Service Pack 1 from 6/2/2006. Which can be found here --> http://www.ulead.com/tech/msp/msp_ftp.htm
Most likely, to state the obvious, the file has probably become corrupt. I believe the update should prevent future corruptions but would not allow you to reacquire an already corrupt file. However, you could try loading one of the .DVP files that Media Studio 8.0 creates when it makes an auto-backup of a project in progress from time to time.
When you create a project and save it, it will save your saved project as a .DVP file in the folder you selected and by under the name that you chose to save it. It also creates a 'folder' in that same location by the same name as the name under which you saved your project. If you look inside that folder there should be a number of other .DVP files that have the same name as your main .DVP file but with a three digit number added to the end of the file-name. These files and their file-names start as <your project filename>000.DVP and with each auto-save it just saves another copy in the same naming convention but the three digit number is incremented by one each time. You could try opening one of these auto saved files starting with the one with the highest three digit number and see if it opens. If it does not open, try another one with the next lower number. Work your way back to the next lower number until you find one that will open your auto-saved project. It may not have your most recent changes or edits but it would be better than losing the entire project.
I hope this suggestion might help you to recover your project. I understand the frustration completely.