Open Task Manager by right clicking on the task bar and select Start Task Manager. Check for wstraydictmode.exe in Processes tab.
If you find this program in the processes list, check the file description. If you identify the file as one of the software you have installed, you may have to stop that program and then install Flash player.
If you can not identify the file then right click on this process and select Open File location. If you have any suspicion about the file being a virus or worm, terminate it from processes list in Task Manager by right clicking on this process and selecting either "End Process or End Process Tree".
Check in Google for this file and verify whether it is a normal file or a virus/worm.
Update your AV software and run it to clean the system and check whether the file "wstraydictmode.exe" is removed from your system.
Once this file is removed from memory, you can install Flash Player.
