What happens in normal mode, are you able to still do things but it takes a really long time, or the computer freezes up?
see if you can get a ComboFix scan to run in normal mode.
Be patient and let it run for as long as possible.
Also, there should be another scan log from the recent scan for mbam (that was a protection log), if you could take a look for it.
If you can't get it to run, then try the following, preferably in normal mode, but if it won't run in normal, run it in safe.
The machine was very badly infected, so there may be some broken services along the way.
Now before starting the next step, be sure you have a current restore point, ComboFix should have created one for you.
Please download Windows Repair (all in one) from here:
Install the program then run the following steps:
Go to step 3 and allow it to run the Disk check (this will check for any bad sectors)
Once that is done then go to step 4 and allow it to run the SFC (system file checker)
NEXT, on the REPAIRS tab => Click the Open Repairs Button
Click the select all check box and then click on Start Repairs.
Please DON'T use the computer while each scan is in progress.
A restart may be needed to finish the repair procedure.
Now run the machine in normal mode and let me know if there is any difference.
As you have XP you are getting limited for your choice of software, but BitDefender and Avast both have a very good free AV