Wireless is playing up

[#1]

Hi guys
I got a 833MHz P3 in the cupboard under the stairs running a rt2500 based wireless card in AP mode. Its been running tickety boo for around 8 months and the laptop has never had a problem locating the signal and connecting to it.
Recently thats changed.
Its struggling to find the signal and when it does eventually get there... it drops again.
Nothing has changed but I've noticed 2 other APs in the area - one has around 60% signal the other around 30-40%. Mine used to be far higher that both - it is literally about 5 feet away from the coffee table where the laptop is used.
So... what are the possible causes of this? - I've tried changing channels and that hasn't helped either. The only time it seems to connect is when the laptop is literally right next to the AP box under the stairs.

[#2]

What channels have you changed from an to?
You could get netstumbler and see the channels the other APs are running on.

[#3]

One step ahead of you before I even started this thread
Netstumbler shows my access point cutting in and out continually. Also the same for the other APs which I find odd.
I'm unsure if the PCMCIA card in the laptop is at fault or if it might be the PCI card in the P3 PC.
I've tried channels 2, 5, 10, 9, and now 6. No difference. It is almost like the card has just decided to stop broadcasting properly yet when the laptop gets closer to it the signal shoots up to 100% - within 1.5feet anyway.
The weird thing is I've not touched the AP box for yonks. The antenna is in the same place as always.
This is very frustrating.

[#4]

have you checked the box in the cupboard recently?  could be it needs a clean and the pci cards re-seated.

[#5]

Get a small am radio tune it off station so there is no noise then put it near the pc and around the area you may find noise emitting from some other device or powerpoint.

[#6]

Have you acquired any other wireless devices recently?  Even something like a wireless or Bluetooth keyboard/mouse set in the wrong place can cause this, also a DECT or mobile phone or base station too close to either unit will kill a wireless network connection.

[#7]

Nope, but like I said, I've noticed 2 other wireless APs recently.
Not that it really matters anymore - I got so fed up with it I kinda battered the laptop. It shut off instantly and now boots in double the time making a few HDD clunking sounds while doing it.
I thought Wifi was smart enough to avoid data collisions - especially when you're using different channels.
I can't be bothered now. I can't afford another laptop, my employer has refused to give any of us a pay rise, moral is at an all time low.