I have notice that some 16 bit programs wont run if Service pack 2 and AVAST antivirus home or pro is instaled. When i uninstal AVAST antivirus, then those programs start normaly.
I click on icon and nothing happend. Joust sandhour comes for a second or two and that is it.
There is some VDD2.reg registry patch,but i recommend that you install avast! 4.5 beta until Final is released. I think 4.5 has this fixed.
O.K. where can i find this registry patch and where can i download avast beta 4.5 version??
No need for the patch. Sofar 4.5 Beta is working fine with 16bits applications here.
Jp, avast 4.5 update work great. When i can expect the finale relise? 
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I discovered what the problem is on Windows XP with SP2. I tried to install the following problems - Terragen, PowerBASIC 7, Dev C++ 4 and Typing Manager 2001. All these programs started to install then abruptly failed with no error message after creating temporary files beginning sc*.temp. Realising these may be 16 bit processes, I checked Autoexec.nt and Config.nt in the Windows/System32 directory. Config.nt contained the following lines:-
dos=high, umb
device=%SystemRoot%\system32\himem.sys
files=40
device=C:\PROGRA~1\ALWILS~1\Avast4\aswmonds.sys
Suspecting that it may be aswmonds.sys that was preventing the installs. I changed the line containing Avast 4’s aswmonds.sys to:
REM device=C:\PROGRA~1\ALWILS~1\Avast4\aswmonds.sys
to test my theory. All the 16 bit programs mentioned above installed with no problems!
Strider,
remove the REM and upgrade to Avast 4.5 Beta.
That way Avast will also protect/scan the 16bit applications.
That REM prevents Avast from protecting them.
Strider, thanks for posting. Although, like Eddy said, this is a known theory…
If you do that, your 16bit (DOS) applications won’t be protected or a virus of 16bit won’t be detected by avast.
Better is upgrading to 4.5 