First, be sure you fully uninstall Norton:
1) Remove NAV through Add/Remove programs from Control Panel. Boot.
2) Use
Norton Removal Tool for Windows 2000/XP/Vista 2008.0.0.21.
3) Boot.
4) Install avast! Boot.
5) See what you get.
Full SymNRT info:
1. Download and save these three files to the Windows desktop:
a)
ftp://ftp.symantec.com/public/english_us_canada/linked_files/tsgen/MSIFIX.bat b)
ftp://ftp.symantec.com/public/english_us_canada/linked_files/tsgen/SymNRT.exe c)
ftp://ftp.symantec.com/public/english_us_canada/linked_files/tsgen/SYMMSICLEANUP.reg2. Run the three files that you just downloaded
a) On the Windows desktop, double-click the MSIFIX icon.
Click Run.
A black window may appear very briefly.
b) On the Windows desktop, double-click the SymNRT icon.
Click Run.
Click Next.
Click I accept the License Agreement, and click Next.
Type the letters and numbers that you see in the white box, and then click Next.
Click Yes or OK at each prompt.
You may need to click more than once. Your computer may be restarted for you more than once.
You may be asked to repeat some steps after the computer restarts.
c) On the Windows desktop, double-click the SYMMSICLEANUP icon.
Click Run, and then click Yes.
Click OK.
3. Boot.
Then, it would be good if you test the Standard Shield in Custom level and remove the open/created/modified files from scanning. Will it help?
Also, the Professional version hasn't an improved load up time compared to Home. The benefits aren't on performance level.
Oh, last, which other programs are being loaded automatically and which others load drivers (security programs) at startup or as residents?