Malfunctioning Homegroup?

I'd search for this myself, but I'm not even sure what's going on.

I think the problem was caused by me leaving my homegroup, but let me tell you what's wrong first.

• I cannot access anything that requires administrator rights (Only user, Admin of course). This means I cannot run CMD as a admin, or look at admin. tools.
• C:\ is not accessible. However, I can circumvent that by going through my libraries or other such short cuts.
• I cannot access my disc drive. (No sufficient rights)
• Steam (The game app) isn't working for "networking" reasons. Perhaps it's lacking write permission somewhere?
• My C:\'s network path is: \\Skynet\skynet (Terminator fan, sue me). Under the security tab, advanced, "Owner" tab: Unable to display current owner. I cannot change owner (You know, not admin). However, it's most interesting that what's listed is: Matthew (SKYNET\Matthew).

So, from this, it sounds like everything of mine was shared to my address (or however it works) within my first Homegroup. Leaving the homegroup (Because I'm the only win7 pc) *I thought* didn't matter, but I inadvertently removed myself from the permissions list. That's my working theory--What do you guys think?

Don't use Homegroup if you have other Op systems you need to network with. You will need to use either Public file sharing or use Workgroup.