Computer was slow; used Quad Reg. Cleaner, rebooted but went to "safe boot" screen; selected 1st item "Safe boot" but the loading stops on crcdisk.sys with a "please wait" message. Removed and replaced the battery and selected "Normal boot." It booted but nothing works, not even the keyboard and touchpad; used the "on screen keyboard" to key in the password but after the desktop comes up, it can't find the network; can't access Control Panel although I can access change/remove programs; can't reset the system to a previous point. Any advice will be appreciated.