A thorough scan is by default and there is no option to change it. And if there was youd be done useing your computer permently lol.
Im not so sure why you think your ISP is the problem. It sounds like your computer is having the problem, you just have not given enough information for a suggested fix. How are you shutting off your computer? Sounds like you are pressing the power button to off or holding it in until the computer "resets" This is not good. Rebooting is a good place to start in healing your computer AFTER a short period of useing it and BEFORE it freezes. Short periods of use (time wise - maybe 30 minutes?) of doing normal things, followed by a reboot. Until this happens finding the problem may be more difficult.
Also someone smarter than me can inform you on how to check on what problems exist, while your waiting for that information, I suggest you not "use it till it freezes" and "improperly shut it off" This is not good practice and is very hard on your computer.
Good luck! Oh and allowing it to finish a task (example: letting a page fully load before you take off to another or pressing the back button to previous page) types of activity are not helping eaither. Until you get things worked out. This is wadding up the computer as well.
My computer always runs ScanDisc after an improper shutdown (which happens too often because my internet provider tends to freeze my computer occasionally). I never used to worry about it because the scan took about 2 minutes. After a recent shutdown, however, the scan took over two hours. The recent scan was "thorough" and I suspect the previous scans may have been "standard." But it wouldn't allow me to change from thorough to standard during the automatic scan. My only option was to cancel, or let it do the thorough search. When I clicked on Microsoft help topics under scandisc, it did not appear to give me an option to preset scandisc to standard scan when there is an improper shutdown in the future. Any advice would be greatly appreciated.