OS = Vista
HP computer about 1 year old
2 GB Ram
Old MOUSE: HP Optical connected to PS/2 Port on back of computer.  At times acts a little erratic, thus the NEW mouse was purchased.
New Mouse: Ativa Optical Mouse (USB) connected to PS/2 port via (PS/2 adapter) on back of computer (same mouse port).

With electricity turned off at my surge protector, I plugged in the new mouse as listed above.  My computer comes on and then prompts me to enter in my user password as NORMAL.  However, it appears that my key board does not work as my password does not type any characters in the box.  I cannot proceed, so I resorted to turning off the computer by turning off the surge protector.  With the computer off, if I reconnect the old mouse, everything works fine and I can type in my password.

The new mouse does work both in the USB port and the PS/2 port on the back of the computer, BUT ONLY AFTER I start up the computer with the old mouse plugged into the PS/2 port.  If I shut down my computer with the new mouse plugged in to the PS/2 port, any subsequent start ups result in the inability to type my password in the password box.

Obviously, I would like to be able to use my computer with only the new mouse plugged in to the PS/2 port.  Any suggestions?
did you run the disk that CAME with it?  It mite be that it needs the driver on it.No disk came with the new mouse.  I did go to the Control Panel and clicked on the mouse icon and tried to have the computer search for a new driver via the internet.  No LUCK...Smae problems.was there one for the old one?No disk for the old mouse either.  It was the mouse that came with the desktop.could you run vistia repair?  i'm not vista knowdgleable.Vista Repair?  I typed that into my help dialog box...Nothing found.I'm not all that vista oritended didnt know if it was still there.I'd return the mouse.From what I'm concludeing I agree with broniMouse returned.  New mouse now plugged in and works flawlessly.  Thanks!genious, glad to see it got resolved.Yeah, just remember: bad hardware straight from the box, happens.
I'm glad, the problem is solved.well its good to rule out the possible solutions.  But as long as its working know.