Why am I seeing "application error" on startup of windows 7 profession

There is a fix. First, you need to know which application is causing the error message. This can be found in Event Viewer/Applications, you will have to check the times when you get the error. If there is a start up folder, you can see if one or more are not showing up using Task Manager.

Once you have identified the application, the next step is to disable the startup of the application. If there is a startup folder, try removing it from there (I don't remember if Win 7 has a startup folder). If there is not a start up folder then the Registry would have to be edited to remove the application from the startup. The Registry is part of the operating system and an error in making changes could end up with a non functioning computer. Click on the start button, select run and type Regedit and enter, the key you are looking for is hkey_local_machine\software\Microsoft\windows\current version\run, look for the application and right click on it and select Delete. You should make a back up of the Registry, just in case.

If yo are not comfortable with this, it is best left to a tech.