I tried searching for an answer but the only common reply is what you have already done so maybe you need to look elsewhere on your machine for a problem. First either press reset button on your adapter or uninstall everything that lets you get on internet and start again.
Next , as soon as you get to desktop bring up task manager and look how many processes you have running in the background , they could be delaying your computer connecting.
Look in start menu , how many items do you have set to launch at start up , this could also slow things down. i only have my anti virus and sound card set to run at boot up.
When you set up your wi fi connection did you use a " secure connection " code to stop others in your area stealing use of...