Try to open Excel in safe mode and check Add-ins.

1. Click on Start > All Programs.
2. Go to Accessories > Click on RUN.
3. Type Excel /safe (leave a space after Excel) > Click OK.

If Excel works properly in safe mode, then there is problem with add-ins. Follow below steps to disable the add-ins:

1. Click on File > Go to Options.
2. Click on Add-ins > select an add-in type > Click Go.
3. Uncheck the Add-ins to disable > Click OK.

Good Luck!