Hi
You could try removing .NET and reinstall .NET as a workaround to check.
Also please understand that Event 1000 and Event 1026 indicates that the problem lies with the application itself, you could reach out to experts in the Xenserver forum:
https://discussions.citrix.com/forum/101-hypervisor-formerly-xenserver/.
Regarding these two Event ID, please refer to the following articles.
Event ID: 1000 Source: Application Error
http://www.eventid.net/display-eventid-1000-source-Application%20Error-eventno-1475-phase-1.htm
Event ID: 1026 Source: .NET Runtime
http://www.eventid.net/display-eventid-1026-source-.NET%20Runtime-eventno-10740-phase-1.htm
Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
I hope this information above can help you.