Multiple problems

I have Win 7 computer with 2 GB of RAM. I mostly use Firefox but have used IE and Chrome and have same problems. I bought something on Ebay a month ago. Two days ago, I went to buy something else and got to the final step and pushed "comfirm and Pay" and nothing happened. I called Ebay and they could not help and said it was my computer. I also get messages that says I do not have enough memory even though I had only 3 tabs open. None of the tabs were high RAM users like youtube. Some pages load very slow. I don't think this is bad because I looked it up and I get isearch.avg.com on every address bar. It is supposed to combat spyware but is annoying. What do I need to do to fix this? Thanks

I get isearch.avg.com on every address bar. It is supposed to combat spyware

My best guess is that's the problem, often what is made to protect us can also hinder us, and it's not always easy to understand how to tell it to allow x process, and with all these Java vulnerabilities being mentioned lately, I can only guess that it's that protection trying to block you from what could be dangerous, this should be able to be told how to add x site to a "safe list" or similar, but I don't know this software so I am just going on similar issues I've seen over the years.

I am hesitant to say to uninstall protection, I would rather find out another option ideally, not unless said protection is no good, but I have never seen or heard of this one, so can't comment at this stage, but the fastest test I can think of would be to disable it and try, launch ie, click on the Cog icon in the top right corner, go down and click on "Manage add-ons" which launches another window, on the left click Toolbars… (if not already showing), then go down the list and see what you have, find this toolbar in the list, highlight it, then select to Disable it (near bottom right corner of that window), close the window and browser, then try to achieve your goal again and see if that helps, if it does that means my suspicion is right, if not we need to look deeper, hope this helps.