Dell screen going wonky, colored lines, black screen, etc.

I'm not sure how to explain my problem.  I'm no where near a Windows/PC/Dell person (I'm a college student, it was the cheapest computer at the time) so bear with me.  This is what it says in my System and Maintenance window on my computer.  I have Windows Vista, a Dell (obviously) Inspiron 1545.  The processor says Intel Pentium Dual CPU. 

The problem?  When I even touch my screen it goes a bit wacky.  It's hard to explain; it starts rapidly flashing a black screen with colored lines (it looks like my windows that I have open are being distorted into colored lines.)  It's really confusing to explain without showing a picture.  I can't use the computer on a uneven surface (it has to be a flat surface, for example a desk).  To "fix" the problem I have to close my lap top and reopen (even though sometimes that doesn't work until I do it like six or 7 times).

The last time this happened I had a Dell (was a few years ago).  I don't have the time to send my computer away for a week or 2 to get fixed..

Does anyone know what the problem is, or is having a similar problem?

If it helps any I bought it from Wal-Mart (which I will NEVER do again..)