Well the windows error 0x00000002 is just '2' which is "The system cannot find the file specified. "
So there would appear to be a problem with your installation, which according to you you believe everything is OK. Changing the default interval shouldn't change the 0x00000002 error and it may be no more than co-incidence. If you were regularly getting Red update alerts (that didn't mention the 0x00000002 error), that may well have been resolved by adjusting the delay.
If you get the 'setifaceupdatepackages error 0x00000002' again, try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.