"I don't think that Citrix really appreciates what we're trying to do with their software," Deal said. "I don't think ... we have any [service-level agreement] from them because they would not guarantee that this was going to work at all for this implementation."

"From what I've read, Epic [is] not very scalable and not very robust, and when you're putting Citrix in front of that -- we have most the most number of Citrix servers in the world -- you're going to have problems," said the IT employee.

Epic officials referred questions about the project to Kaiser.

Scott Herren, group vice president and general manager at Citrix Systems Inc.'s Virtualization System Group said the issue isn't scalability, it's really about the overall system architecture being set up to accommodate loads of that size. Kaiser is using Citrix's Presentation Server.

He said these issues do not stem from the Citrix product. "In fact, we have many very large successful Epic deployments around the world. However, in order to support large deployments, the Citrix implementation must be architected accordingly," Herren said.