HP problem?

Hi. I have had this problem before and it seemed to have gone away, however it's back. I just tried to type an email to Cyberpower and it's as though I was missing a lot of letters when I typed with any speed and when I'd go back to correct it several words were together and I'd have to re-type the whole thing. What I mean is if I'd type something with a letter missing and try to insert it I would be missing the letter from the next word etc, and as I typed the next letter would be missing, so on and so on. Hope this makes sense.
If so, could someone tell me if it sounds like the PC or my ISP?

Sounds to me like your keyboard and PC are not communicating properly.

What happens if you toggle the insert key on your keyboard? (INS key, probably near HOME key and DEL key)

Ok, will check both out. The strange part is it doesn't happen all the time but I think it mostly happens on emails. Thanks Drac and Jenny100.