blast this internet and its odd problems!

ive been on a trip for a week or so, and i was glad to get back to my computer. suddenly this afternoon, something goes wrong. my internet connection works fine, but for some reason internet explorer and msn messenger dont recognize that there is a connection there. so i can only use the internet via mozilla. its not a terrible end of the world problem, but this is really really annoying. ive cleaned out any and all spyware through ad-aware. multiple times. ive done virus checks with pc cillin, and even went through a registry clean. so whats going on here? if anyone knows what the problem is and how to address it, that would be most appreciated.

i had a similar problem. I had a fresh install of xp, and it would work fine if i connected straight to the modem. As soon as i went through my router, net would still work, i could get on messenger and stuff, but ie and opera both wouldn't connect. I dropped a spare NIC in and now it works fine. Stupid settings must be screwy somewhere.