What's wrong with my computer?

[Lisalips]

I have an applemac and every 20 seconds or so any video I'm watching will freeze even though the audio carries on and also every 20 secs or so whatever I'm typing will stop or if I'm moving my mouse the pointer will freeze and the small spinning ball will appear. Please help as this is doing my head in as things that used to take seconds or minutes now are taking a lot longer. Is it a bu or virus maybe? Are there any free debugging programs or anything I can do?
Please help!

[Lisalips]

Help? :(

[madmaggot]

I'm no expert but in the absence of an answer I'll volunteer my thoughts. It could be that you don't have enough free temp memory space.
Have you tried a disk cleanup?

[Milvus]

Could you give some more info a bout your mac type etc. Click the Apple logo top left, then about this mac, that will give you the op system release and memory. Then click the Finder icon, the first icon on the dock, at the bottom of the window, it will give you the amount of disc available. It may be you are running out of free space. You won't have a virus. Let us know the info above and then we can suggest a route to clear the problem