1. Avoid virtual CD-ROM
Now most virtual CD-ROM is not stable in Win XP, which easily causes system crash, because virtual CD-ROM is different from general software: with special mechanism, in “Device Manager” it cheats Windows, letting Windows think just physical CD-ROM, and XP only designs recovery hardware driver, haven’t thought to “Recover/Delete” hardware yet. As XP is optimized especially for NTFS and network, while most virtual CD-ROM is developed under FAT32 environment. So far there’s rare virtual CD-ROM software, if you have to install one, then you’d have to endure several times’ system down to try which one is stable. Probably XP might get crashed.
  Especial warning:
Even you’ve found the stable virtual CD-ROM software, if you virtualize more than 4 physical CD-ROMS, then probably XP activation inspection mechanism might be triggered, asking you to activate XP again—because Microsoft thinks that you might change the machine if change four pieces of hardware. Therefore, suggest you not to install virtual CD-ROM software.
 If you do want to, then you’d better to use multi-system, Win 98 system is much better. It seems that you’d only have to wait for the virtual CD-ROM software designer to develop new version could run stably and need no activation.
2. Avoid invalid date
XP has one date check mechanism matched with activation inspection. If your motherboard CMOS battery is out of power, or by wrong operation or