theburninator92 :
Hmm, it seems to be doing the exact same thing today even though automatic update is still turned off.. Was what you told me to do just a temporary fix until I did a reinstall or is it showing signs of a different problem?
Rundll32.exe is a program that allows for standardized launching of shared logic contained within DLL files. DLL stands for Dynamically Linked Library. DLLs contain program code that is dynamically linked into a program when it is run, as opposed to statically linked into a program when it is compiled. This allows for easy portability between operating systems provided that the interface is the same.
Rundll32.exe simply allows for named routines contained within DLLs to be launched without creating a program specifically to load and launch it. It's not uncommon for a few to run for a short period of time, nor for some to persist in the background. However, since it's a well known program name, malware occasionally masquerades with the same name. Under task manager you can enable the "Command Line" column to see exactly what was invoked for the process that's chewing up all your CPU time. You should see something along the lines of "C:\Windows\System32\rundll.exe <somefile.dll>,<some function name> [function arguments]".
If the task does not begin with "C:\Windows\System32\rundll.exe" then it may be malicious software that is simply trying to obscure itself by adopting the same name. Without knowing the dll and function, it's not possible to know what's causing the problem.
As a side note, you should reenable automatic windows updates