It's just happened again in 6.0.6.8996. I heard a few beeps after I hit F5 to compile and debug, but it didn't even save my changes, let along compile.

Then the same WEL error dialog appeared with GetLastError 14. This is the first time I've seen the dialog since I originally reported this problem.

To monitor the desktop heap, I installed the utility recommended by the link you sent me a week or two ago. Here's the output produced while the WEL error dialog was still open:

$  \WINDOWS\system32\kktools\dheapmon.exe
Desktop Heap Information Monitor Tool (Version 8.1.2925.0)
Copyright (c) Microsoft Corporation.  All rights reserved.
-------------------------------------------------------------
  Session ID:    0 Total Desktop: (  6336 KB -    7 desktops)

  WinStation\Desktop            Heap Size(KB)    Used Rate(%)
-------------------------------------------------------------
  WinSta0\Default                    4096             53.9
  WinSta0\Disconnect                   64              4.5
  WinSta0\Winlogon                    128             19.5
  Service-0x0-3e7$\Default            512             38.8
  Service-0x0-3e4$\Default            512              4.3
  Service-0x0-3e5$\Default            512              6.8
  SAWinSta\SADesktop                  512              0.5
-------------------------------------------------------------


Now I'm no expert on interpreting this, but it appears to me that I have plenty of desktop heap.

I had to kill EiffelStudio to recover from this.