Just guessing here as you didn't give us a lot of info...
I assume there are at least two slots for the RAM. Did you remove a single 64 Mb stick and replace it with a single 256 mb stick, or did you remove two 32 mb sticks and replace with a single 256?
Some machines require pairs of RAM and you may need to install two sticks for it to work correctly.
By the way, in my opinion, 256 mb is a bare minimum for Windows XP. I suggest more, IF the motherboard allows for it.
Hope this helps.
My friends pc runs very slow with windows xp.
He is running a P3 500 with 64sdram pc100.
I tried upping the ram to 256sdram pc100 and the monitor stays in standby mode. Put the old stick in and works slowly. Exchanged the 256 thinking it may be faulty but still does the same.
Can anybody please help me.
Many thnx anyway