Originally Posted by dafinof
i want to install ubuntu 11.10 on my computer but keep my win xp
ubuntu can`t detect my xp and see my hard disk empty and suggest to erase it all
My best guess is that you have misunderstood the choices during Ubuntu install and it can actually see the xp partitions, and it can see there is currently no room outside the windows partition to install Ubuntu.
First step is you need to have unpartitioned space for installing Ubuntu. Have you done that yet? If not, it is best to do so before using the Ubuntu CD as an installer:
First step of the first step is to boot up xp and use its internal tools to defragment the partition. In some cases, doing that well requires disabling and deleting the paging file, then defragmenting, then later (but not right away) reenabling the paging file.
After defragmenting the windows partition, you should boot the Ubuntu CD in liveCD mode (not install mode) and start up the GUI partitioning tool (I don't recall Ubuntu liveCD details well enough to know which GUI partitioning tool is there or how to start it, but it shouldn't be too hard to find).
At that point, you should see more clearly whether you were correct that Ubuntu can't see the Windows partition, and you would have better tools for looking around to get info to support asking for expert help. More likely, you'll see Ubuntu can see the Windows partition and at that point you would shrink that partition to make room to install Ubuntu.
After shrinking the Windows partition, I would reboot Windows, which tends to force a disk check. If paging was disabled, I would reenable it. Then make sure Windows is still healthy.
THEN you are ready to start the Ubuntu install, which should make more sense now that there is a place for it to install.