Apps Sudden mysterious ADB failures

[Slug]

I realise this is a long shot, but I figure that if anyone has a clue it will be someone in this forum. Right now, even with Mr Google's help, I'm stumped.

I've had the Android SDK (r7) installed on Windows 7 (x64) for ages, and ADB worked. No IDE; I use ADB for rooting/hacking.... shell, push/pull etc. I made good use of it to root my Desire Z at the end of November.

Last night I went to check something in relation to a member's query and got "failed to start daemon" errors. Sometimes it would return "daemon started successfully" immediately followed by "daemon still not running error: cannot connect to daemon". On the odd occasion that it does connect, within seconds it then disconnects. Here's an example of what I'm talking about:

C:\Users\Alan>adb devices
adb server is out of date.  killing...
* daemon started successfully *
** daemon still not runningerror: cannot connect to

C:\Users\Alan>adb kill-server

C:\Users\Alan>adb devices
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
List of devices attached
HT972L905058    recovery


C:\Users\Alan>adb shell
adb server is out of date.  killing...
ADB server didn't ACK
* failed to start daemon *
error:

C:\Users\Alan>adb kill-server

C:\Users\Alan>adb shell
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
/ #
C:\Users\Alan> [disconnected and returned to CLI prompt within 5s]

Netstat shows repeated unsuccessful attempts to bind to port 5037. I've tried updating the SDK to r8 with no success. Ditto updating the JDK. I've uninstalled all possible Windows updates and hotfixes back to Xmas (the last time I can remember ADB working) to no avail. DDMS runs fine but ADB is a dead duck.