After further investigation, I answered my own question. For some reason
EXCEL.EXE properties was set to open using 256 colors. I unchecked the
option and everything started to work correctly. For those who encounter
this problem again here is how you fix it:

1. Go to C:\Program Files\Microsoft Office\OFFICE11
2. Right click on EXCEL.EXE and select "Properties"
3. Select the "Compatability" tab
4. Check the display settings and ensure that they are what you want them to
be.

"Hannahspapa" wrote:

Whenever I open Excel it changes my screen resolution to a lower resolution.
How can this be prevented ?