will rebbot my system every time

[georgegerm]

i cannot get avast to do a complete scan or check c: without it rebooting the system

which can be a pain if im doing long downloads online
i have reinstalled and checked the registry entry for it being correctly installed
more ideas are needed  

windows xp pro

[Eddy]

Run chkdsk first to see if there are problems on the drive. Also disable all running programs when doing a full system scan.

[techie101]

george,

This may occur if Avast has been corrupted or improperly installed.

Repeated reboots are the default behavior when Windows XP encounters a System failure. This behavior can be changed by going to the System applet in Control Panel, select the Advanced tab and click the Settings button under the Startup and Recovery heading. Under System failure, un-check Automatically restart.

This will only prevent the reboot.  I would use the Repair function of Avast:
Start/Settings/Control Panel/Add-Remove.
Double click on Avast.  Select the Option to Repair.

Reboot system and try again.

The recommended troubleshooting method would be to shut down all non-essential programs to see if Avast will run a full scan, then put one program back into the Startup one at a time until it stops the scan or reboots.

This way we can isolate the offending program and figure out what we might do to correct.

Think positive.