Well I can't swear that it did it to you too, but Diamond Tweak has mistakenly implemented changes on mine even if I closed through the X instead of choosing OK, so I wonder if by some chance it tweaked something for you that it shouldn't have done so.
That said, give me about 15 minutes and I'll update this again... I'm testing out the 4 column update (though this definitely wouldn't cause a manila.exe error, it might cause a shell.exe issue if it wasn't implemented properly).
UPDATE: Confirmed that the 4 column update is correct and should work without issue.
So... did you use a cab or manual edit to get rid of the SprintTV tab and Music Store link? If you did it through a program or cab, which program? If you did it by hand, copy paste the contents of 090661f7_manila and 26948339_manila in a private message so I can make sure you didn't accidentally strip out too much (I've accidentally removed </> closing tags on several occasions.