Hi t0bias,
aMule (as any other user space program) cannot cause a kernel panic by itself.
I believe you should run memtest in your machine and see if your memories are behaving. Also check your disks to see if there is any problem with bad sectors, but most probably it is memory. Could also be a high temperature in the CPU, check your fans. And assuming you have hand compiled your kernel, make sure you used your distro recommended compiler, it is not any version of gcc that is able to compile a kernel reliably.
Cheers!