Isass.exe system error (on title bar)

This probably is not a virus as this newly installed PC has Panda antivirus updated. Can’t tell if it’s L, i or 1 at start. The message box says ‘I/O error operation initiated by the registry failed unrecoverably. The registry could not read in, read out, or flush, one of the files that contained the system’s image of the registry. New PC with Celeron 2800, 256MB, 40GB, Win XP Home, SP2,.