If you are having the "Not Enough User Rights" problem when you try to update or install Avast Free then I think I might have the solution (or rather a solution that does not involve throwing your PC out of a window as I came close to doing when I had this problem).
I have a PC running Windows XP Professional 32-bit SP3 and had been running Avast Free without problems until recently. As I rarely use this PC, the Avast program (v.6 free) on it was out of date and needed reregistration. Re-registration was successful, but then the program refused to update either the AV definitions or the program to v.7.
I tried many different approaches - including those suggested on this and other sites - until I found a pathway that seems to work. When I tried to install v.7 I kept getting a series of errors, most notably the one saying that I did not have enough user rights to continue - even though I was logged on as an administrator.
The following seems to work:
1. Download both the Avast uninstaller (aswclear.exe) and the latest Avst setup from the Avast website. Make sure that the Avast that is currently installed (if any) is registered or re-register if necessary. At this stage it might also be a good idea to disable any firewall or any other AV/Security program running (just in case it runs when in Safe Mode)
2. Boot up into safe mode and make sure you are logged on as an administrator.
3. Run aswclear and when it is finished reboot again into safe mode (again as an administrator)
4. Open regedit and for each of the groups (such as HKLM) check that the account you are logged in on has Administrator and read/write permission. If not, highlight the group by right-clicking, select permissions and give your account that permission. I did this for each of the main groups HKCR, HKCU, HKLM, HKU and HKCC - though it is possible that you may only need it for HKLM.
5. Try and run the Avast installer - you might get the Not Enough User Rights error; if so, open the log and look at the last line. If it is telling you that it cannot create a particular entry (such as HKLM\Software\AVAST Software\Test) the reopen regedit and go the the location of this entry. Select the entry by right-clicking, or the AVAST Software entry if no children entries exist, and check the permissions - you will probably find that you are not shown as having read/write permission. So, give yourself that permission, and re-run the Avast installer.
6. Hopefully AVAST will now reinstall successfully.
7. Reboot into normal mode, check that AVAST is running and go to the maintenance setting and update the AV signatures.
8. Make sure that you restart your firewall and any other security programs.
This should now enable Avast to run successfully.
