HASHBYTES comes at an additional storage cost, but not always as high as 8000 bytes as mentioned in your post.

Like danny.heijl points out it is only 16 bytes for MD5...

If you are logged in with administrator privilege on the laptop then restart the SQL server service with the -m switch and then log in using windows authentication.

Not all types of error rollback the batch transaction.

Try this out:

--create table

create table test(a int not null primary key)

--execute following statements

begin tran

insert into test values (1)

insert into test values...