IMac mouse problems / strange behavior (impossible to configure mouse preferences)

Question

I work in a design and communication school, the used hardware is iMac (Intel) whit Lion (OS X 10.7), we have several rooms equipped with these Macs where students light up their data on the server.
Today, 3 of these Macs had problems with the mouse, including mine.
Basically the clicks don´t work correctly. We cant close windows, open folders or change some options by clicking, but we can open softwares, scroll.
In safari if i search something, when I try to click the link i want, safari opens a new tab instead the one i am at, and has other strange behaviors. So I´ve tried to change the mouse settings, and when i make a change, for example: change the scroll button to "buttun 3" the mouse automatically assumes all buttons to dashboard, but not at the configurations window because it says that scrool button still "button 3",  when i use the click or the scroll or any button it just slid me to dashboard or a setting that has nothing to do with my option.
This is really causing a big problem since we are a school.. I already tried to change the mouse, clean, try another usb ports, search for update or restart but it still doing the same.
I think it have something to do with an update.. but not sure.. would be really gratefull if someone knows how to solve this.
As a temporary solution,i disabled all options using only the mouse click, but to do it, i had to plug in my tablet (that works perfectly for the record) and use it instead of mouse (since it was impossible to use it), than went to mouse preferences and disable left click, scroll and side buttons and then restart the Mac (or else it wont work)..
it will work fine but still a problem cause I use all mouse buttons custom as well as the students...

Answer 1

I have been experiencing a freezing mouse as well. I updated the mouse drivers but it is still happening. I have been repairing the permissions and noticed something very strange see the mention of a -t. I have been running unix systems since 1984 and have never seen that before....
Determining correct file permissions.
Permissions differ on ./Library, should be drwxrwxr-t , they are drwxrwxr-x
Owner and group corrected on ./Library
Permissions corrected on ./Library
Permissions differ on ./private/var/log/secure.log, should be -rw------- , they are -rw-r-----
Owner and group corrected on ./private/var/log/secure.log
Permissions corrected on ./private/var/log/secure.log
Permissions repair complete
Permissions differ on ., should be drwxrwxr-t , they are drwxr-xr-x
Owner and group corrected on .
Permissions corrected on .
The privileges have been verified or repaired on the selected volume
I reported this to Apple and they told me to erase the hard drive reinstall the
system. I really don't want to have to do that. It seems like something is taking
control of the machine.....