I have exactly the same problem with my FX140. I have all the update drivers/software patches form the sony site but still no go. Mine is a 550/700 but it seems to run at 550 80% of the time. I can set a profile to use in powerpanel and set that as default, but it only stays at full speed for a few hours, then defaults back itself or after a reboot. I have emailed Sony but haven't had a response back yet, but I suggest you do the same. The more responses they get, the better the chance they fix it quickly. BTW do you get the speed control icon in the sys tray?? I bloody don't!

Have you tried wincpuid ? Its a great little program that among other things tells you the cpu speed. It will at least tell you what the actual speed of the cpu is. ( www.h-oda.com )

I love being on the phone with tech support and solving a problem myself . . . called Sony, as I was talking to them I was digging around in the settings. I had downloaded WinCPU ID as recommended - great app!
 
 
For you laptop users, got to the CONTROL PANEL --> PERFORMANCE AND MAINT --> SYSTEM --> HARDWARE --> HARDWARE PROFILES
 
Highlight Profile 1
 
Select PROPERTIES and -- ready for it? --- simply click THIS IS A PORTABLE COMPUTER
 
Docked,undocked, unkown settings dont seem to matter. Keep in mind I went into BIOS (F2 on reboot) and set it to MAXIMUM. Not sure that matters but I am not going to change it to anything else.
 
As they say in jolly old England ---- Huzzah!

FANTASTIC! It works! the profiles still don't stay at the set default, but it works at full speed now! great work Dan!

Well, I thought it was all working at full speed, but it turns out that's not quite so. System tells me that it's running at 700 but then a few seconds later it says 550 again. WCPUID comfirms this. If I keep hitting refresh, I can see the speed changing from max to min a few times a second. Surely this isn't good for the CPU. I just hope that this is fixed soon, it's really yanking my chain!!

Try removing all of the Sony speed step crap and then running it native in WinXP. In BIOS Make sure the chip speed is set to MAXIMUM.
I would also play with the docking settings. Im seeing mine change on reboots but in rality your laptop should never be shut off -- just hibernated.
 
Its a matter of finding the right combination

I've tried everything I can think of and what you have suggested. I ran the WCPUID realtime clock watcher for about 15 mins. THe processor just keeps changing it's speed dependign on what seems to be the amount of usage. It jumps to full speed and min speed all by itself, no matter what the bios is set for. I have had 2 bios updates in the past week, so maybe Sony are still working on probs such as this. We can only hope

Give me a day or two to tinker .I have to laptops, my wife's and mine. I dod not follow the Sony recommended upgrade scheme, just updated, removed the sony crap and been tweaking. I had the speed problem on mine.
 
 
On hers -- same FX190, I followed sony's directions and have not seen the lower speed I dont think. Ill keep an eye on it and let yo knowwhat I findout.
 
I am seeing my speed jump around too, Let me see what her's does. We'll figure it out. If anyone reading this has the Sony programs running and is NOT seeing a speed change prolem let us know. Software should NOT affect the chip speed --its a BIOS setting. If it is then Sony has to answer to their customers.

I had the same problem with my notebook running under battery power. For "energy-saving reasons" (a MS employee told me), the "presentation" and "max battery power" settings in the power scheme will reduce the clock speed. So, under those settings my computer drop from its usual SpeedStep speed of 500MHz to 64~220Mhz. Changing it to "minimal power management" increased it back to 500.

You were pretty darn close. I tried it, but it didn't work. HOWEVER! I set the power management to be "Always On" and what do you know??! FULL SPEED!! thanks man, I knew it would be a simple fix