These kinds of malware can be quite clever. For example, it might start a service on reboot that copies and renames a file in your system32 folder, such that no matter how many times you delete it, the file will pop back up again. Or, there will be a buried registry entry that controls its propagation. Or there will be a rootkit.
If you don't want to reimage your PC, then you will have to go through a multi-step process that will investigate services, registry, temp files, windows shortcuts, startup folder, and browser extensions and plugins.
There are a handful of good sites where people will actually go through the steps to help you remove malware. Typically, they will ask you to install a piece of sniffer software, then post the results to the forum so that it can be investigated.
You might try this page for additional removal instructions:
http://malwaretips.com/blogs/remove-istartsurf-virus/
Or this one:
http://www.techsupportall.com/how-to-re ... oval-help/
You might also get help from this forum:
https://forums.malwarebytes.org/index.p ... oval-help/
PS: I don't like MacAfee. You installed the stuff that is infecting your computer... it didn't magically jump onto it from an internet infection. This crap gets installed when you install some kind of freeware, and you fail to uncheck all the boxes about installing additional 'free', 'helpful' software... and sometimes the freeware just installs this crap anyway.
This stuff is called PUP - potentially unwanted program, and your anti-virus should be able to detect it in the download files for the install. I use Webroot, and it is almost a pain in the ass because it detects stuff as PUP that I do want to install.
Edit: A couple more forums where you can ask for help.
http://www.bleepingcomputer.com/forums/ ... oval-logs/
http://www.geekstogo.com/forum/forum/37 ... e-removal/