Not sure if this relevant but I have recently seen some problems with Panda Internet Security on brand new kit. 2 possible solutions.
1 - Try stopping the XP wireless util and using the software provided with the net 2 plug h/ware.
2 - Find and rename "netflt.sys" this will stop the Panda unknown threats service (this is Panda's solution).
Solution 1 worked with Fujitsu Siemens PC's but not with Acers. Solution 2 (only tried with the Acers) worked for a few reboots but then failed.
nb The wireless hardware was D-link.