My computer is behaving strangely tonight. Firefox is going to the wrong URLs and Internet Explorer will not open, or closes immediately.

The computer I use is wired to the router for our home network. It is an older Dell that runs Windows XP Professional. My McAfee antivirus subscription ran out 2 weeks ago, but I hadn't renewed it yet because I am trying not to spend money. Both my husband and I use this computer to access the Internet. My husband prefers Firefox, I prefer IE, except my LnC shortcut is saved in Firefox.

This afternoon I was in Firefox and I googled an item I needed to buy. The first link that came up on the screen was an Amazon URL, but when I clicked on it, a bunch of strange URLs started loading, and the browser went to a non-Amazon URL that had nothing to do with what I was searching for. I tried a second time and the computer loaded a bunch more strange URLs and the browser went to a second site that I did not want. I closed Firefox and tried to open IE. It opened but closed immediately the first time, then would not open the next 3 times I tried. When it finally did open, I got a message that Internet Explorer had encountered a problem and needed to close. I got that response the next 3 times I tried to open it.

Using a third browser (AOL), I went to the McAfee site and renewed and upgraded my antivirus subscription. It automatically turned on the McAfee firewall, but since I already had the Microsoft firewall turned on, that made it impossible to open anything. I turned off the McAfee firewall, but now the computer is still slow and I still can't open Internet Explorer without an immediate message that it needs to close.

Has anyone ever run into anything like this before? Could it be a virus? AOL did pop up and say it had found adware. However, when I told it to remove it, it did not show anything in the "removed" listing. I have not yet run a complete McAfee scan but I will be doing so later this evening. Is there anything else you would suggest? I don't have the free week I would need to remove and reinstall everything on this computer.

Thanks in advance for any answers.