looking at the domain you have conflicting A records in your zone file.
Your www record is pointing to the correct IP but your Master A record is pointing to 2 different places. Thus only some of your employees being able to load the pages, because one of the IP's is not the correct one..
host remtulla.ca
remtulla.ca A 198.147.41.48
remtulla.ca A 192.168.0.3
host
www.remtulla.ca
www.remtulla.ca A 198.147.41.48
Long story short you need to contact Whom ever manages your Zonefile and remove the "remtulla.ca A 192.168.0.3" record.
If you want a further explanation or more assistance with your website/hosting/dns issues. Hit me up via PM, this is what i do for a living!
This took me 10 seconds to find your issue. You should consider finding a new administrator/IT guy. This was very straight forward to resolve.