Some Apps refuse to open or close after few seconds. it apps or phone iPhone 4S

Has anyone else suffered from the following glitches? A few apps I have purchased recently have worked fine for a couple of days but then seem to stop working. By stop working I mean an app is pressed, the screen flashes to black as though opening the app, but then fails and returns back to the original screen. This has happened on two apps thus far, shiftlife organiser and the free app movie SFX. I had to delete them and re-sync them on ITunes. They both appear to work fine for a few weeks and then fail to work for no obvious reason. Another app Met Office Weather, will open correctly, but when navigating through the app to say weather maps, just shuts it down continuously. A game Death Rally, which I have been playing on and off for a while with no issues, now will open for a few seconds and then close itself again. Another issue is functions not appearing. From the main menu screen I have flicked left to the search screen to find there is no keypad, or when accessing ITunes via the phone, cannot input the ITunes ID as there is no keypad to enter the password. On each occaision i have rebooted the phone, but I dont want to have to keep performing this manual fix each time. Its almost appears as though a virus is slowly infecting my Iphone 4S V5.0.1.  HELP!!