sentinel & Happy,
The simple answer here is this ...
MetaStock 7 is not 100% compatibility with Windows XP
The only version(s) that are 100% tested with Windows XP is 8.x and 9.x
There is not patch or fix for versions lower then 8, so there is nothing that anyone can do to help you on this matter; The only fix is to upgrade to either 8 or the current version 9.
If you have time on your hands you can play with the compatibility settings XP has, but it will help a little but it will not make the program 100% fixed. So I'm sorry to be the giver of bad news.