I had few issue with SP1a too. Then i suspect different chipset could be causing the issue.
My 845MP chipset that had SP1a works fine, although the OS is pirated but i paid the license. Just dun like the recovery CD for my laptop.
My 865PE chipset that had SP1a dun work fine. One moment, it disable my control panel's add/remove software. next moment, it disable my USB features... And the OS is the same CD i used.
Then again, you can always use a firewall whilst updating ur Sp1.
PIV 2.6Ghz w HT 512k Cache 800Mhz FSB
GA 8IPE1000 PRO
Twinmos 1GB DC 400 CL2.5
120GB IBM 7200RPM w 2MB cache
120GB Maxtor 7200RPM w 8MB cache
Nvidia FX5200 128MB
Philips SXGA 150S4 15\" LCD
Cooler Mastor Centurion
Global WIN Cooling System
TDK Cyclone 48X24X28X CDRW
Intel PRO 10/100 TX
Sigma IrDA Port
PixelView FM/TV Pro