I have installed ubuntu 12.04 inside windows 7, and love to try it,but I don't know why it slows down and windows become grey while installing updates or using software center and that causes "un disfonctionnement total" of all system can I find how to ride over this?
If a window becomes gray, it means that it is busy.
You have some options to "fix" this:
The software center and update manager both are pretty ressource-heavy applications. Depending on your system you might want to consider using command-line tools as a replacement.
To install software:
To update your system (in this order):