MeDIeVaL you should Only ever have one resident (running) Anti-virus program on a system at any one time (more is not always better).
If you have more than one AV program running you can be sure they will conflict. 3 running AV programs = trouble
AntiSpayware programs are a little different. Again only one with resident protection enabled the others used for additional checking.
AVG anti-spyware has a 30 day trial then becomes non-resident or you can turn this off when first installed
Spyware Terminator you can turn off the resident shields
SUPERantispyware free is non resident
Ad-Aware SE Personal Edition non-resident
Spybot Search and Destroy Tea-Timer off
I have all 3 of the above installed (non-resident) without any problems