I'll agree with Abdon- it sounds like the front shifter has moved the chain to the small chainring.
If you always leave your bike in its "highest" gear, you're not riding it efficiently and you're wearing out parts in the drivetrain instead of sharing the duties among all the gears. You should either learn to use your gears or change to a dedicated single-speed bike.
__________________
Jeff Wills
Comcast nuked my web page. It will return soon..