FileMaker 7 and 11 files use the same format so no conversion is necessary nor even possible.
Likely, your file is corrupted. It may appear to work fine in one version and yet trigger crashes in another.
Recover the file, using FileMaker 11 and see what is reported.
Best Practice is to not use recovered files, but instead replace the damaged file with an undamaged back up copy if at all possible. You may have to save a clone of an undamaged back up and then import your data from the recovered copy into the clone.