Weird hard drive activity when I open folders

When I first start up my pc, whenever I open a folder with files in it, if I haven't opened that folder since it was shut down, my hard drive starts accessing and my mouse pointer turns into the little circle while it's waiting for something to finish. At that point I can't do much of anything until it's finished, which takes around half a minute or so usually. It happens with a folder with media files in it, and even just text files. What could be causing this? It's very annoying. Could it be my antivirus (Avira)? Is Windows doing this? Could I have some setting enabled in Windows that causes this to happen? Once the folder is opened and it stops whatever it was doing, it won't happen again until I shut off the pc and open that folder again. It seems something is scanning the files in the folders when I open them.

Could it be my antivirus (Avira)?

Quite possible.

Is Windows doing this? Could I have some setting enabled in Windows that causes this to happen?

Probably, might check the Indexing function.

Berton said:

Could it be my antivirus (Avira)?

Quite possible.

Is Windows doing this? Could I have some setting enabled in Windows that causes this to happen?

Probably, might check the Indexing function.

Indexing is off.

lehnerus2000 said:

If the folder contains pictures and/or videos windows may be generating new thumbnails.

Do you use a System Cleaner (like CCleaner)?
If yes, check the clean up options and make sure that "Thumbnail Cache" isn't selected.

Yes, I do use ccleaner and another system cleaner. Thumbnail cache is selected to clean. How can I check thumbnailing in Windows?

Can I disable thumbnailing?