Java HotSpot Virtual Machine

I have a problem that seems unrelated to traditional GC tuning. Full Garbage Collection on my server (x86, Linux, 2 proc, 2GB memory, 1GB Heap) is taking in excess of 10 minutes. The frequency of the Full GC is about every 8-10 hours. I've combed some posts for issues related to long GC, but long is a relative term, and usually refers to 2-10 second range.

My question is, what kinds of things could cause such an extremely long GC. My theory is that this particular machine is hosting some other applications, most notably a mysql server that is connected to remotely. With this setup, another application could be using resources on this primary server while the Full GC is executing, thus causing a thrashing scenario from a CPU perspective. But even so, it seems that this wouldn't cause Full GC to take 2 orders of magnitude longer.

I've currently changed to the CMS garbage collector, so the long pauses are not a problem, but I'd really like to understand why such a long Full GC pause is even possible, and what can be done about it using the serial Collector