My CUV4X-V had this problem. It was working great for about 3 weeks, until I tried to plug in a new-old-stock keyboard. I'd get stuttering input, and it was unusable. USB port worked for a few days, and then that failed as well.

I found this thread and pulled off my C151 capacitor and bam, everything is working fine again!

Thank heavens for website like this and for people posting these findings!!

I dug out (2) old CUSL2 m/cs from the loft as I need something with a 'real' floppy disk interface.

Needed a lot of tarnish cleaning from contacts but worked OK but after a while the keyboard stopped responding. Tried lots of things and eventually left it for the day. Next day it was working again??????
but in the mean time the IDE interface stopped working - I now think a faulty Disk has killed the FW82801BA Northbridge - orderd one off eBay and will try replacing just for the hell of it.
This disk causes a scrolling 'H' on the screen on boot up. A different disk passes the POST test but then hangs. The IDE interface and keyboard interfaqce are both on the same chip................

In the meantime the second machine.
Also needed lots of cleaning.
(They have both been in the loft for many years and damp seems to have got at them 🙁 ) Some rust on the printer port.

Straight off the bat, the keyboard was misbehaving causing the BIOS to make funny noises. After a few minutes - keyboard not present error every time.

That was when I found this website. Tested C151 and the segment on the keyboard connector had a low resistance (approx 1KOhm) on a digital meter - not showing dead short maybe because the test voltage is not very high - didn't try my old analog meter.
Checked the other machine and there was an OC reading.
Removed C151 and hey presto the keyboard is working again - phew!

Was now able to boot into Windows XP and the USB mouse was not working. Tried cleaning the USB port connections - no change. Added an extra USB card and the mouse was OK.
I then spotted between the USB port and the printer port there is a jumper marked USBPWR (USB power I guessed) I removed this and cleaned the contacts and jumper and now OK again - another phew!!
I assume this is for when all your USB devices are externally powered.

One 256MB RAM sticks is not working. Have cleaned it but will try more intensely.

I am amazed at how fast this 933MHz thing is running 32 bit Windows XP. If ir could I'm guessing Windows 11 would take about 3 weeks to load.

More to follow as this progresses.
As an aside a stupidity. I had the case propped up while testing (the one with the faulty IDE) and it slipped with a USB cable plugged and and has broken one half of the dual USB socket - now also ordered from eBay. Doh!