aka
robert_e_bone
It sounds like you have a bunch of viruses on the computer, and if you wait until AFTER you suspect they are there to download antivirus software, it will also be affected by the viruses.
It used to be that if you bought anti-virus software from the store, that you could boot from it and scrub your ailing drive of any viruses. I have gone soooo long without viruses that I do not remember how one would create a similar boot disc to do the same
Avast seems to sell one for like $10. Here is one from Kapersky that seems to be free: http://support.kaspersky.com/4162
You definitely want to download and create the disc from a separate computer, and THEN boot up your computer to let it scrub. If you have trouble booting to the CD drive, you can start hitting F12 during start up to display the boot menu, or you can alter your BIOS boot priority settings to make your CD/DVD the first bootable device. Look for the 'hit any key to boot from DVD' message and hit enter - or some other key.
Anyways, I hope that helps.
When I remove viruses from people's computers I take their physical drive and plug it into my computer, which then sees it as a data drive, which means that any viruses on it will not boot up into my memory. I then use MY Avast antivirus software to scrub their drive.
At any rate, you have some things to check into and decide. I DO think that weird behavior like that is an indication that you have some 'critters' in your computer.
Bob Bone
Sorry Bob but most of that just isn't true
Downloading an exe file for antivirus software cannot be corrupted by a by a virus that already exists, it just can't
Removing their drive and plugging into your computer carries many risks
You don't need to download to a separate computer. Many virus infections will block the well known sites anyway. The safest way is to start the machine in 'safe mode with networking' thus bypassing all of the startup files which can harbour potential infections
oh and to the OP - (once again) run Malwarebytes
You are correct on your first point - I actually to type it as download/install, rather than just download. The check sum validation on the download should take care of the download - installing it on the machine that is already virus-laden can infect programs getting installed, as the viruses are already in memory, (and who knows were on the hard drive).
I have HAD a virus install get infected, and it does happen. All bets are off when there are viruses loaded into memory and on the hard drive of an infected computer.
Please understand I am not beating my chest with this part of my post - I am explaining my understanding in a moment, and if that understanding is not correct then please do enlighten me. There's LOTS I do not know about computer, despite my work background.
I do not understand the risks you refer to in my plugging in a hard drive from another computer into my system.
1. It is seen on my system as a 'data' disc. Nothing on that drive will do anything unless I cause something to access that drive. The first thing I do is run a boot-scan of my entire system, that drive included - to get the rest of the infected files off of the other drive. I just let it run, keeping an eye on infected files and counts.
2. As far as I understand it, my exposure window to viruses from the infected drive is any that are created/altered/unleashed in between the last virus update (happens several times a day on my system), and the time of the boot-scan and cleanse of the hard drive. That's a pretty small window. I also take complete images of my computer at least once a week on a regular basis, and do so too prior to loading an infected drive as a a data drive on my system. I can restore my computer from the image in the unlikely event a virus got through.
So, again, just laying out my understanding of this aspect of it all,
Bob Bone