What font is used in your solution?
I recommend to use a font that is available natively on Mac and Windows, like Verdana.
Check out the new FMDiff 2.0 to compare two FileMaker files and test for file corruption at <http://www.fmdiff.com
i was using Arial font , and change style too .. but i think it problem btween filemaker 9 and windows 7 cuz everything work fine when open my application on filemaker 11 but unfor my customer using filemaker 9 XD
Not all versions of Windows use the same font metrics for supposedly common fonts. Try setting the tab object to Verdana plain text style. If that doesn't work try Times New Roman plain text style.
If either of those does work, then you have a font mismatch on your other font choices between versions, and need to keep your font choices extremely simple.
The fact that it appears fine on some computers but not on another strongly suggests it's a local font problem. If neither of the font tests above work, check the installed and FM-configured fonts on the problem machine.