DSI.PVWA.Host.exe is a component of PaperVision Web Assistant, most likely it became corrupt because of a virus. You may want to check if your system is infected by performing a scan with your antivirus, if you don't have an antivirus program installed, I recommend avast! Free Antivirus.
Also your problems may be registry-related, in that case you could use Registry Mechanic , it detects invalid or obsolete entries in the system registry that may cause this issue.
After performing this checks, if you encounter the same error, try to uninstall PaperVision Web Assistant and install it back again after rebooting your PC.