My slingplayer would run only once after install. After contacting support, they had me delete files It would then run, but again only once. Support was stymied - told me I needed to get a new computer. Then I found the exact same issue with another of my computers. Since I'm not going to buy 2 new computers, I investigated and made a batch file that would delete the files needed and then launch the player. Don't know why Slingmedia didn't figure this out, also don't kn ow why they thought it appropriate to smear the player with their obnoxious ads. Anyway, here's the .bat file that worked for me. You may need to change the path for your specific computer:
del /S /Q "C:\Users\media pc II\AppData\Roaming\Sling Media\WebSlingPlayer\*.*"