The 00000005, Windows error 5 = Access is denied.
There may well be a legitimate reason for access to be denied, but this one may be a Trojan and something is protecting it (google search for the file name
http://www.google.co.uk/search?q=shmgrate.exe). See one of the google returns,
http://www.liutilities.com/products/wintaskspro/processlibrary/shmgrate/.
If you can try to upload the file to virus total for a scan, check the offending/suspect file at:
VirusTotal - Multi engine on-line virus scanner and
report the findings here. I feel virustotal is the better option as it uses the windows version of avast (more packers supported) and there are currently over 30 different scanners.
If you have XP, vista32bit or Win2k, you could enable a boot time scan. Right click the avast icon, select Start avast! Antivirus, Menu, 'Schedule boot-time scan...' Or see
http://www.digitalred.com/avast-boot-time.php. This may well be able to scan it outside of windows and possibly bypass this protection.
The boot-time scan might take a little time but may well be worth it just in case there might be something else, rather than use the advanced options to restrict the scan to the system32 folder.
What is your OS, XP Home/Pro ?
What is your firewall ?
If you haven't already got this software (freeware), download, install, update and run it, preferably in safe mode and report the findings (it should product a log file).
1. If using winXP or Vista
SUPERantispyware On-Demand only in free version. Or
Spyware Terminator Resident scanner (if you use this don't install the toolbar or crawler or the anti-virus module). Or
a-Squared free On-Demand only with free version(if using win98/ME).