Ok I work as an Internet Tech support so I am familiar with this issue. If you always lose the connection at a certain time, I would check two issues. Take a look around your house for anything that comes on at 7. A coffee maker, TV, anything that uses electrcity. What can happen is that the electrical noise from a device leaks through a break in the coax cable. It can be a micro crack you can't see. Stop anything that comes on at 7 for the next day. If you don't lose your internet you have found the area that has the bad cable. Schedule a tech to come out.
The second and harder one to solve is that there are too many computers connections in your area. There is a device called a CMTS that servers as a huge router to connect you to the internet. Inside these giant routers are cards called blades. Each black will have up to 6 upstreams, possibly more depending on how your isp updates its cmts. You are on a single upstream on that blade. If they have too many people on that same upstream you will experience a contention and utilization problem that will cause you to loose a connection. This isn't usually a specific time problem like you described. It happens during the high points of usage after work into the late evenings. What can also be happening is that you have someone on the card using too much of the bandwith. When I see this problem, it is someone running a server or serving as a host for a lot of bit torrents. When they come online they will hog the bandwith and it can cause a problem.
To get your company to work on a bandwith problem it is best to keep calling in to report the issue. Tell them you know someone in a cable company, and ask them to have the upper level techs check this out and send it as a issue to the network operations center. Keep polite, but be insistent. Ask for credit. You should be able to get credit for your internet while this is going on if it is a area issue. Expect it to be around a month before this could be resolved. It takes a bit to move connections around on the cmts.
Anonymous Tech, January 2008