Packard Bell iMedia A887 P4

Question

Packard Bell iMedia A887 P4 3GHz 512MB ATI X300SE 128MB PCIe 160GB Win XP MCE 2005 (NEC)Boots up OKVirus scan OKControl panel: System select comes up with rundll32.exe application not found...yet file exists in system32 folder.Also any application file selected causes a list of programs to select from coming up.rundll32.exe file replaced! no changeDesktop - OKExplorer - OKPlease help.