You're welcome Steve.
Since the easier options didn't work out for you, these more drastic options should be able to fix it.
If this has only started happening not to long ago, then you could do a system restore
using a restore point dated before it started to hopefully fix it.
If not, then you can do a repair install
to fix this without losing anything if you used a retail Windows 7 installation DVD to install your Windows 7 with.