After installing Presentation Server 4.5 Rollup Hotfix 02 the following error may be seen when logging into a desktop session:

VMwareUser.exe - Application Error
The application failed to initialize properly (0xc06d007e). Click on OK to terminate the application.

It is not seen with published applications as they do not start explorer.exe which in turn starts VMware User.exe from the Run key:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"VMware User Process"="C:\Program Files\VMware\VMware Tools\VMwareUser.exe"

Possible Workarounds:

1) Obtain the private hotfix from Citrix
If a support call is logged with Citrix support you will be able to access a private hotfix that resolves the issue. This will be publicly available in the coming months.

UPDATE 1/5/08: This is now a public hotfix
http://support.citrix.com/article/CTX116967

2) Remove VMwareUser.exe from the Run key
If the "VMware User Process" is deleted from the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run key the issue is resolved. There may be some loss of functionality from VMware Tools e.g. Drag and drop/copy and paste operations which does not seem to affect ICA sessions.

3) Use icammdrv.dll from Rollup Hotfix 01
This is not recommended, has had practically no testing, and there will almost certainly be regression issues doing this, but it does remove the error message.