Car Shudders while accelerating

[dsc919]

I bought my 02 s80 just over a month ago and all seemed fine until today.
My issue is that while I'm accelerating there seems to be a shuddering in the front end of the car, almost like driving over a washboard. It had me concerned because even the slightest attempt to accelerate resulted in a shudder. I did have the air conditioning on for an hour or so in stop and go traffic so I'm not sure if that had something to do with the problem. While cruising at 100k/hr I turned off the a/c and 15 minutes later I had no more shuddering and I could accelerate with out issues.
Anyone have an idea what this is caused by or suggestions...
Your help is realllllllly appreciated.