You could check the hardware manual for your 1150, its online at dell somewhere, on how to remove the keyboard and then manually clean it.  I have a 9100 and I've had to take my keyboard out and clean it too.

 

This may be helpful.

Refer the link that explains, "How Do I Troubleshoot an Unresponsive Keyboard on my Dell™ Inspiron™ Computer?

In the link given above you will find information on how to clean the Keyboard.

Refer the link to open and clean the keyboard.