Girl is off/on

Hey again,

You were all very helpful last time and things have progressed. However I still have not got around to asking her out - pathetic I know.
It's just I'm still in this state of mind that she dosn't like me and is just messing with me. On Friday she told me I should go to a party that she was going to on Saturday night, I couldn't because of work. Anyway again she was really freindly on Sunday, but today (Monday) she completely blanked me in college? WTF??
Am I susposed to go and talk to her, if so how do I go about this without making myself look like a total dick infront of her freinds??

I guess I just want to know if any of you have ever done this to a man. - if so why? Because at the moment she is just making me feel like she dosn't like me.
Is she not speaking to me because she wants me to engage in conversation first? Does she just want to know if I like her and she will know I do if I talk to her first? Is she embaressed to be seen speaking with me? (I don't think this is the case as she wouldn't have asked me to a party and there is another girl at work who also goes to our college who she speaks to me infront of).
Any way some help would definatly be appreciated. Sorry about the length of the post (again).

Thanks

Maybe she's getting frustrated about how she appears to be getting nowhere with you. She's probably saying to her friends, "Damn! Why won't he ask me out?"