And just to add my voice to the torrential downpour, I too have been blocked from my local airports slot page!
I'm not especially upset but it has highlighted to me the problems with the system as it stands currently.
Based at EGKK/LGW I am at an airport with reasonably significant slot congestion. I was not however refreshing the page to see if more slots were available, in my case, I visited the page a number of times whilst putting together schedules for three new aircraft, requiring me to view the page a number of times to see which hours I could actually have my aircraft depart.
Contrary to the interpretations of the algorithm, I was not refreshing the page to gain an uncompetitive advantage, so as to see when a whole new set of slots were available, but simply refreshing the page a few times (through my own mistakenly closing the separate window as is my habit) to see what time slots are available.
The other problem, as already highlighted, is that there are no indications as to when it will again be possible to access the slot page. Or perhaps more accurately, the stated time is not in fact accurate.
Problem 1 - There is no clear rule on how many times you can access the page in a given period.
Problem 2 - The indication of when access will be permitted again is inaccurate.
Problem 3 - Checking the page again after 10 minutes *seems* to cause the period of your being blocked to be extended (this I do think is unfair)
All that being said, I'm not too worried, just chilling for a few hours before I try and gain access again.