Thank you jholland1964 for your reply. I was running the latest version of MBA-M as you can see from my previous post, I did update right before I clicked full-scan. I do not have Virus Doctor entry under Add/Remove programs and Search came up with nothing. So I do not think that I have 'Virus Doctor' installed on my computer. Also don't you think 'Virus Doctor' would have shown up on the HijackThis log? Somewhere on the internet I read that the popups can be launched from a trojan hiding on the machine - do you think this might be where its coming from?

If the pop ups and redirects are there then chance of you having it on the computer are pretty good. You won't necessarily see it in Add/Remove.
Your logs show clean, both of them but that doesn't mean it isn't there.
check the Task Manager for ANY or ALL of the following processes:
VirusDoctor.exe
VDocf360.exe
unins000.exe
VDo[RANDOM].exe - the RANDOM means then name can be anything at all.
I noticed in your HJT log that taskeng.exe was running, this is a scheduled task. Check in your Task Scheduler for unusually named scheduled tasks

I looked in task manager and saw no processes by those names. Then I checked Task Scheduler and found 4 suspicious tasks whose name is a GUID. I'm not sure what they are for?

Here is the name and action of the tasks:
Name: {56B404BE-4B0C-4965-90E3-4F0FE52D093A}
<Command>C:\Windows\system32\pcalua.exe</Command>
<Arguments>-a "C:\Users\jzelenak\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\JF6T2N5G\sp40702[1].exe" -d C:\Users\jzelenak</Arguments>

Name: {BD8D371B-A791-4AB7-853B-784FC7146413}
<Command>C:\Windows\system32\pcalua.exe</Command>
<Arguments>-a "C:\Users\jzelenak\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\I51H596T\sp37093[1].exe" -d C:\Users\jzelenak</Arguments>

Name {DC17124A-5505-4BFB-8D4F-D439D397C35A}
<Command>C:\Windows\system32\pcalua.exe</Command>
<Arguments>-a "C:\Users\jzelenak\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5\6VF6RG9R\sp39689[1].exe" -d C:\Users\jzelenak</Arguments>

Name: {F9E2DDA7-832A-4D05-8DEC-51D66FB64A4A}
<Command>C:\Windows\system32\pcalua.exe</Command>
<Arguments>-a C:\Users\jzelenak\Downloads\med\Install_Netter.exe -d C:\Users\jzelenak\Downloads\med</Arguments>

Can you please tell me what these tasks are for and should I delete them?

All list <Command>C:\Windows\system32\pcalua.exe</Command>
usually this refers to the Program Compatibility Assistant
The first three listed may be:
sp37093.exe Broadcom driver
sp39689.exe Fax Modem
sp40702.exe possibly an HP NIC drive.
Did you download and install some new drivers from someplace other than the manufacturer's websites? All references also are pointing to temporary internet files..
The last one which is however listed in Downloads\med...meaning medical? Did you install some medical reference material? Possibly via P2P file sharing?

I have HP laptop and I was installing drivers from their website and the med one was from a friend through network but it failed to install(don't know why, maybe corrupt file?), so I wonder can I delete all 4 of them?

Oh and what does Program Compatibility Assistant do?

From WindowsHelp Microsoft
The link above gives other information so you can check all that on that site. Sounds to me though that these drivers you were installing were older drivers than Vista normally requires.

Here is also the Vista Compatibility Center

There have been several versions of malware going around that can cause this. Malwarebytes takes care of most of them. Some alter the hosts file at windows\system32\drivers\etc. Right-click, select open, from the list of programs select notepad. If there are a lot of IP addresses followed by websites, this may be your problem. Just delete the entries, or rename the file.