mouse confusion

My problem began when my ps/2 mouse started going crazy while i was playing starcraft. I shut down and tightened connections then restarted. Now my pc wont detect the maus. I tried a serial mouse still nothing was detected – i made sure all the com ports were enabled. Now i removed my modem to free some resources. Only the serial mouse worked. Weird thing is that when i start starcraft everything freezes. Even the video completely disappears. Do i need a new motherboard???? I already reloaded anew copy of the bios in case it got corrupted. Help!!!!