Maybe you want to print a newline?

print "checking website...\n";
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Otherwise, I wonder what you expect an infinite loop to do, other than making your program run forever...

Explanation for Corion's proposal: Suffering from Buffering

Perl is happily printing your string into a buffer every minute. Had you waited 3 hours and 35 minutes, you probably would have seen 215 copies of the message appear at once.

Yes, I need it to run until stopped, which I have written an input sub function which changes the variable to 0 which should then stop it. but problem still remains that the loop never runs when its called and locks it up

Surely the question still remains, how do you know ...that the loop never runs... ? By ...it locks up..., I assume you mean the caller, aka the script, which if true, surely implies that the loop is indeed starting and as Corion and ikegami have both already pointed out, you (or more accurately, your script) is 'suffering' from buffering.
A user level that continues to overstate my experience :-))
</div

use Schedule::Cron;

# Create a Cron object and assign a coderef to it
my $cron = new Schedule::Cron( \&check_website );

# Establish the time interval between runs.
# This follows the standard cron notation.
$cron->add_entry("* * * * *");

# Run cron job.
$cron->run();

sub check_website { 
   warn "Checking website...\n";   
   # code
}
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instead of sleeping, and calling a sub to stop the loop, write the loop like this (pseudocode):

while (!alarmed) { 
   yourWorkHere();
   alarm("you have 60 sec. to press a key to stop this loop");
   if (keyPressed) { alarmed=1; }
}
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First, you don't show the code that "checks the website". Maybe something like this will work?

use HTTP::Request::Common qw(GET);
my $url_target = "some_url_to_check";   # like: http//x.y.z.com

while  (my $url = GET $url_target)
{
   # $url contains some text here that you process...
   # this means that the GET function succeeded.
   # the GET is a "blocking" dunction and waits until it gets a
   # "yes" or "no" answer;
   
   sleep(60);  #We don't know how long the last "get" took
               #but we are going to wait 60 secs before we
               #try it again...
}
else
{
   die "Opps there is a problem";
   # this will happen maybe about 1/1000 attempts
}
;

I would recommend some sort of control on the number of
trips through the "else" clause to prevent program
infinite loops.

#perhaps like this:

use constant MAX_RETRY => 5;
my $retries =0;
while  ( my $url = GET $url_target)
{
   #do something here..as above....
   $retries =0; 
   sleep(60); 
} 
else
{
   $retries++;
   if ($reties > MAX_RETRY)
   {
      die "maximum tries exceeded";
   }
   next;  #try again...
}
;
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