Need help recovering from an "optimizer" app; clarification in message body...

Hello all,

  I made the mistake of using a so-called "optimizing" app on my computer.  It's a XPS/Dimension 400/9150, but I upgraded to Windows 7.  All was well... then I used this app.  I won't name it unless someone says that it's okay to do so.  It made wonderful claims that it'd fix this and that, speed up certain things, etc.  Well, now my computer is screwed...

  When going to "My Computer", the only drive that shows up is my "C" drive.  I'd love to know what happened to my CD and DVD drives, as they no longer appear.  I discovered this when I went to copy a DVD to my hard drive.  Also, I use Firefox as my default browser.  It's hard to describe its bizarre behavior; if you click on anything (including to "X" to close the browser!) it'll take several repeated attempts before anything "takes".  I don't want to say it "reloads", but it does kind of... I'm sorry; I don't know how to describe it.  Though, I tested Internet Explorer and it works fine...

  Yes, I have tried reinstalling the drivers, reinstalling Firefox, etc... but nothing's working.

  I've used apps in the past that claim to "enhance" a system's performance and I should've known better, as those apps never really seem to do any good.  However, I've never encountered one that messes with your browser, makes drives disappear and such.

  Can someone please help me to possibly resolve some of these issues?

  Thanks in advance,

  Justin