Blank page with ADSSP login script at logon

Blank page with ADSSP login script at logon

Hello,

Some users are using XenApp desktop over Windows 2012R2, and when they logged in, they experienced a blank page which can't be close without killing the process.
The blank page is the login script to ask users to register.
Even if they killed the process and proceed to register in ADSSP web page, at the next logon they will still have the blank page whereas they registered.
Not every users on those servers are impacted.
On others computers, we don't have any problem.

Is there prerequisites on Windows 2012R2 for the logon script (ADSelfService_Enroll.hta) to run ?
Do you have any idea what can block ?

Thanks,

Regards 

Anthony