It's my first topic here on PlanetZ

I have pulsar2 6 DSP, sfp v4.5 installed on my new computer: intel i5, asus p7p55d-le and 3 giga DDR3, running windows XP and cubase 5.
when I set my ULLI to 25ms (44100 ) there is no problem, the computer is working great!
the problem appears with lower ULLI values, 3ms for example:
when I open cubase5 (or SX3), clicking F12 I see that my ASIO/CPU meter is going crazy, jumping and unstable, even before opening the cubase project!
before I bought this computer I had a P4 that didnt have this problem, even in 3ms.
I tried reinstalling cubase, sfp, the drivers. NOTHING...
The creamware card is on IRQ17, alone.
Help please...