since you state you can not find any other monitor I assume you also mean generic so you may need to run if X config tool does not work....a manual tool
most distros have such...try with root powers
xorgconfig (mine is in /usr/bin) and follow the prompts but before you do...make sure you have backup of your current file and know how to use a live cd to re-store its name if your new file causes a crash.
It is generally better to edit /etc/inittab to a runlevel (i am guessing redhat's) to a non-x one of 3?....your file may tell you.
the reboot....login and change to root and then run
if no errors....next command gets gui
then edit inittab back to old setting maybe runlevel 5