Most computers run their fans on full speed when the system is first powered on. It's generally a BIOS-controlled function.
Also, when your computer first starts up and the Operating System loads for the first time, it runs a lot of checks, loads drivers into memory, and starts services as well as any programs you've installed that run all the time. All this means your CPU and other system components are getting a lot of use.
It is normal for it to take a few minutes for your computer to complete all it's necessary processing and to settle down for smooth running.
Using startup manager programs you can see see many of the programs set to run on start and may help resolve your freezing on start up issue.
In summary: I wouldn't worry about the fan running high. It's not a serious issue and is not normally indicative of any sort of problem.
I would worry slightly about your computer needing to be hard reset on load from time to time, but there are other questions that deal with that here on SU.