Why is my Ad-aware scan taking more than a day to complete?

Q  Something appears to have gone wrong with my Ad-Aware installations. Previously, it has always carried out a complete scan in no more than around four hours – and sometimes less.

However, the latest scan has now been running for over 24 hours – and it still hasn’t finished. This surely cannot be right?

I have already tried completely removing and reinstalling the program but to no avail. Do you have any idea as to what might be causing this?
Brian Delves

A  You didn’t tell us if you have anti-virus software installed in addition to Ad-aware but we’ll assume you do (and if not, you should). The reason it’s relevant is because some anti-virus programs have settings to automatically scan and check every file that is opened or even just accessed by other programs.

This boots-and-braces approach makes some sense, because it means nothing gets past the attention of the anti-virus software – but it can slow down a PC considerably. Indeed, in most circumstances, it’s probably overkill.

More to the point, we think it may be the cause of your problem. When you ask Ad-aware to perform a full scan of your PC, it is tasked with accessing and checking tens or even hundreds of thousands of files and documents. This process may take hours – and that’s normal.

However, at the same time – and as explained – your anti-virus application may well be responding to Ad-aware’s activities, subsequently checking each file that the spyware-removal touches. Of course, for a full scan, this in fact means every single file, slowing down Ad-aware’s work still further.

Our suspicion, then, is that Ad-aware’s sloth-like performance is the result of your anti-virus program’s behaviour. As for why it has recently become so much worse, we wonder if you have recently updated or installed a later version of the anti-virus software?

If so, this may have resulted in new default virus-scanning options – including checking every file that is accessed, known as on-demand scanning.

As noted, this heavy-handedness is great for security but terrible for performance; most people are better off limiting on-demand virus-scanning options to downloads and clicked links and so forth, while relying on regular scheduled virus scans for in-depth checks.

Unfortunately you didn’t tell us which, if any, anti-virus program is installed on your PC so we can’t offer more specific guidance here.

However, look in the application’s settings screen for a ‘resident shield’ (or similar) option. Here you should find tick boxes to enable or disable various methods.

We’d advise disabling any options that instruct the anti-virus program to check existing files as they’re opened or closed, but leave on-demand scanning enabled for new downloads and inserted media, such a discs, USB memory keys and so forth.