Hi,
1. What is the exact and complete error message you get when you try to set higher resolution?
2. What is the make and model number of the graphic card?
The issue could be with the cable as the issue began after changing the cable, I would suggest that you change the cable and check if the issue persists.
Also see:
Ways to improve display quality
http://windows.microsoft.com/en-US/windows7/Ways-to-improve-display-quality
Getting the best display on your monitor
http://windows.microsoft.com/en-US/windows7/Getting-the-best-display-on-your-monitor