This dialog box pops up everytime I log on or restart my computer, asking "Open With." This is new and never occured before. How can I delete this? I use Windows 7. I haven't downloaded anything new either.
I might be wrong but it sounds like a somthing is trying to run on startup but it doesnt know what program to use to run. go to start menu and type "MSCONFIG", then go to the startup tab. This may take a while to do but untick a box that you dont recognise and restart your machine, if it still comes up, go back into msconfig, re-tick the box and untick another, keep doing this until you find the program which is trying to run at startup.
you have something setup to run on startup/logon, might be by accident (drag and drop) or some thing was uninstalled or updated leaving a file type unassociated.
somethings can be found start>programs>startup. anything on this list will run on logon.
other things are in the registry. you can edit somethings safely by running "msconfig.exe" you can findin it through the search menu.
you can use this tool to find out what program/file is giving you the dialog box by disabling one item at a time on the startup tab. then you can trouble shoot what changed.