I just happened the same, I suspect it is something external, maintaining store
Settings / Applications / Manage Applications / All / Download Manager
Clear data should be sufficient, but I think it is temporary.
Edit: Do not work for me, or at least it was temporary, he was installing to Fever and gives the same error
Error 927
. problem:
The playstore is being updated, download / install applications it is impossible
. solution:
Wait for the application of playstore finish updating to a new version
If the problem persists, go aa Settings> Applications> All> Services Google Play, clean cache and force detention Do the same with Google playstore application