Now been me I got paranoid and ran everything through several web scanners and did several scans of my pc with a couple of on demand scanners and everything came back clean but i would like someone to look at the log files and give it a once over to be safe.
As this is not the first time you got yourself in problems (iirc), it is really time to change the way you are using the system/your browsing habits.
A good start would be using a limited account for daily use and not a account with admin rights.
My last big issue i had was half a year ago with the whole Hola unblocker thing which i dont use anymore. The issue with where i thought my pc was taken over because the screen kept going black was because of the official league of legends screensaver i installed and it messed up somehow and the mouse moving was because i found out my desk isnt 100% level and the slightest nudge makes the mouse move abit.
also with my browsing habbits i rarely stray from a set number of sites, tumblr, 9gag, gaming news websites (eg kotaku), youtube and a number of webcomics i read.
Most of the time i post an issue is because i suffer from terrible anxiety issues and accidently clicking something i thought was an image which sends me to another site that might be bad kind of sets off panic attacks. Even though nothing could be wrong.
not really though my browser does seem tiny abit laggy but that may just be me noticing things that arnt there. intense paranoia tends to mess with your head abit.
SA.DAT is a file that stores scheduler task information. Its date changes at PC startup, and any time new tasks are scheduled. If you have scheduled tasks, they will have file entries in this directory with an invisible .JOB extension on the name of the task.
just want to bring up that my explorer.exe has been crashing more than normal. the first crash was on the 25th at 11:39 pm about 2 hours after i accidently clicked the link (the faulting module was C:\Windows\System32\msxml6.dll)
next one was on the 27th and was caused by PWRISOSH.DLL and another one today with an Unknown faulting module
the first one has me worried as the msxml6.dll is used for jscript
edit: i forgot to mention that when it crashed the first time it was a few mins after restarting my pc