Memory upgrade causing interference??

Ok... I have an issue here that someone might be able to clear up.

I currently use Pro Audio Monitor speakers as my main speakers for just about everything that has a stereo mini out (1/8") jack, including my laptop. I have cable which goes from stereo-mini to 2 1/4" inputs (which go into each speaker respectively). This worked great, until I noticed a very hi-pitched frequency being emitted from my speakers (very very high, almost beyond human hearing). This only happens when I plug the speakers into my laptop. I upgraded my ram from 1GB to 2GB a month ago or so, and I think that's when I started noticing this hi-pitched frequency. It's very annoying. It is like morse code, every few seconds it emits either a short or fast tone. It sounds like something from the laptop is interfering with the speakers somehow. Perhaps someone here may know a thing or 2 about this? If so, your help would be appreciated. I can no longer connect the speakers to my laptop because it is just too annoying!

Thank you.

 

Question - what type of RAM configuration did you have a month ago, 1x 1GB? If you added another stick in there for 2x 1GB then the RAM is now dual-channel so that may be the cause of this. I have no idea why however.