Gradual slooowing, Double identities! RUN!

ok I have a problem.

I noticed today after setting up a proxy program and connecting two other pc's to my network my main PC is showing up under network neighborhood as two diff names.

Mark
Mark a

Everything was 100% last night after I got everything hooked up. But today all of a sudden two names are showing up. I ruled out logging in wrong, and the DNS host names are MARK so thats not it either, and the ID of this pc is just MARK. Where for the love of God is this other name coming from? It use to be Mark A, then Mark and was fine until today.

OS is win98se.

Second im getting crappy internet performance from this PC today all of a sudden also, and last night after everything was hooked in it was fast and responsive on the internet. Today there was long pauses when trying to get my mail and long pauses to load pages, but my other PCs hooked in are running FAST.

Any IDeas on how to troubleshoot this please let me know, im lost.

Thanks,
Mark