HP Pavilion Slimline S3301F (p/n KE553AA). Windows Vista Home Premium 32bit. Windows fails to start. The Safe Modes and Last Known Good Configuration also fail to start. Startup Repair log details say 2 boot-critical files are corrupt, ndis.sys and netio.sys. System Diags. all pass... CPU, RAM, and HDD, and the computer passes POST. Check Disk (chkdsk /r) in UBCD4Win completes. No errors reported. The only recent changes are that I have disassembled and cleaned the computer, applied new thermal paste to CPU, replaced the RAM with OEM-spec sticks from another HP, replaced the CMOS/RTC battery, and reset Time/Date in BIOS. Afterwards, the computer worked perfectly, and completed 3 shutdown and restarts. But when I powered on the computer today...this. The computer did not come with a recovery disk, only a Recovery Partition on the hard drive, and atm, the only OS disks I have are generic XP Home, XP Pro, 7, and Linux (Ubuntu and Fedora). Any help would be greatly appreciated. Thanks much.