Hi,
As Alexis information, please make sure you have installed the Citrix Registry Patch - Enable_Citrix_API.reg with administrator right. Please restart the machine after that.
Please check DEP - Data Execution Prevention is disabled on LR machine as well. You can refer this document to disable it:
http://support.openview.hp.com/selfsolve/document/KM747283
And you can consider to install the patch 1 for LR/Vugen 11.52. This is the link to download the patch 1:
For full LoadRunner: http://support.openview.hp.com/selfsolve/document/KM00484042
For Vugen Standalone: http://support.openview.hp.com/selfsolve/document/KM00484044
Regards,
Chau