Sorry about that. Looks like it was changed to diagnostics after 2003. This looks like the path for 2007.

Excel
Click the Microsoft Office Button image, and then click Excel Options.
Click Resources.
Click Diagnose, click Continue, and then click Start Diagnostics.

I also found this for 2010 version which may be the same as the 2007 version

Windows 7
Click Start > Control Panel > Programs > Programs and Features.
Click the Office program you want to repair, and then click Change.
Do one of the following:
In Office 2010, click Repair > Continue.
In Office 2013, click either Quick Repair or Online Repair.
You might need to restart your computer after the repair is complete.

Let us know if this helps.