Am also getting big problems on Win XP SP3. After upgrade to version 7, start was slower, including the BIOSTAR display right after power up or restart. Then it hung a long time on the black screen 'Windows XP' with the moving blue dots, then it proceeded to start more slowly than ever.
Next day on power up same thing, long dwell (30-40 secs on BIOS screen then it indicated windows had had a power interruption, offering options to start to the last known good configuration and the various safe modes. I chose 'last good set up'. It proceeded to start, again hanging a long time at the black screen 'Windows XP' with the moving blue dots, before continuing its slow start.
Today on power up, again very long hang on BIOSTAR, then untra-long hang on black screen 'Windows XP' with the moving blue dots, before I lost patience at pressed reset. I could not get it to start even in safe mode before again resetting and going to last known good config. Again hung on black screen 'Windows XP' with the moving blue dots, so I decided just to leave it even longer. About 3 minutes later it went to the logon screen and proceeded to start fully very slowly.
This is so disappointing as updates have previously been faultless. Because of the long hang at the bios I wonder whether that is somehow affected. Even if I hit [DEL] to get into the bios setup (not that I know what to do when there) that takes some time to appear.
I was ready to give up and take the pc down the shop to get them to fix it.
What would anyone recommend? Looking at other threads it seems some are OK after a clean install of Avast 7 whilst others are not and revert to 6.