In my daily life I am an avid user of Trados Studio 2014. In my humble opinion it is not the very best CAT tool ever made, but it is quite easy to work with. For more advanced tasks I use MemoQ, which I love for it’s intelligence but hate for it’s bold interface. But when I use it, I like it.
Until last week: I got a MemoQ mscorlib error which rendered the translation software useless at all. None of my installed versions, MemoQ 2013 R2, MemoQ 6.2 and MemoQ 2014 (what I love is that Kilgray unlike SDL allows to install different versions) did work any longer.
However, the solution is nearer than you think…

Signs and symptoms of a MemoQ mscorlib error

You can recognize the MemoQ mscorlib error easily: as soon as you start MemoQ you will see an error message with a General error.
When you unfold the “More >>” button, you’ll see a lot of text. Under the heading “SOURCE” you’ll see mscorlib mentioned.
Scroll down until you see the last line. Here you will find a line with “Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderList”.
What happened is this: the file with all your project information has been corrupted for some reason. MemoQ therefore cannot show a list of all projects you completed.

Solution for the MemoQ mscorlib error

De-installing and re-installing MemoQ won’t solve this problem.
What you actually need to do is go to the following file location in Windows Explorer:
– Windows XP: C:\Documents and Settings\Profile Name\Application Data\MemoQ
– Windows Vista and later: C:\Users\Profile Name\AppData\Roaming\MemoQ
Don’t forget to replace the orange Profile Name with your own name!

Now look for the file ProjectRegistry.dat.
Remove this file and start MemoQ again. That’s all.

Consequences of this solution

Unfortunately removing ProjectRegistry.dat will result in a blank screen in MemoQ: all projects are gone now.
Good to know that your actual projects still exist in their original location. However, you need to open them all one by one to see them back in MemoQ.

Success!