I was having a problem with Apple's SyncServer.exe (part of iTunes). It was choking on the length of my system PATH environment variable (2388 bytes), so I temporarily hacked it below 2047 bytes, and it worked OK.

BUT I couldn't use Control panel/System/Advanced Systems Settings to restore it to what it was previously as that complained that the variable was too long.

To quote MSDN:

The maximum size of a user-defined environment variable is 32,767 characters. (omitted) Starting with Windows Vista and Windows Server 2008, there is no technical limitation on the size of the environment block.
Luckily I was able to restore my PATH by using regedit to change the variable Path stored at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment which doesn't appear to suffer from the problem of the control panel.

Is there any chance this will be fixed (ho ho).