BleepingComputer.com: I'm losing connection with servers every 20 minutes or so.

Hello there. Here's my situation. A few months back I had rebuilt my system. The basic specs are as follows:

Gigabyte GA-890GPA-UD3H mobo.
AMD Phenom II 955 @ 3.2GHz
4GB DDR3 RAM @ 1333MHz
EVGA GTX470
Dual 320GB hard drives in a RAID-0 configuration
Windows 7 Home Premium 64-bit

In the months since I rebuilt my machine everything seemed to be working fine. But on Sunday or Monday of last week (the 12th or 13th respectively) I could no longer maintain a constant connection to a server for longer than about 15 to 25 minutes. Now if I'm just watching a show on Hulu or reading a forum page it is of no consequence, but if I'm playing an on-line game (such as Bad Company 2), having a voice chat session on Skype, downloading a large file that may take longer than 20 minutes to complete, or doing anything that requires a constant connection of some type, I would routinely lose my connection after anywhere between 15 minutes to 25 minutes. This has happened, without fail, every single time I attempted any of the things I have mentioned. The drop in connection would be brief. I'm typically able to reconnect immediately, but every time I do, the amount of time the connection would last would become just a little bit smaller. In one instance it went from 22 minutes, to 17 minutes, to 14 minutes. So far, I've tried the following things to rectify the issue:

1) I ran Malwarebytes, emsisoft, spybot, and combofix to check to see if there was a malware component to this. While I did find a very minor infection on my computer, it did not rectify the issue.
2) I released my IP configuration and renewed it. No effect.
3) I ran an SFC scan and switched my method of connecting to my LAN from a wi-fi card to an ethernet cable. Again, no effect.

I should also note that no changes (to my knowledge) were made to my network prior to this problem. I am operating an RCA broadband modem (model# DCM315), an Asus RT-N12 wireless router, and a Linksys phone adapter (model# SPA2102-R) for my VOIP phone service.

At this point, I am completely out of ideas. I'd hate to go through all the trouble of wiping and reloading my system if it can be avoided so if anyone has any suggestions as to what to do from this point, I'd be very appreciative. Thanks!

This post has been edited by AspirantMage: 18 June 2011 - 09:26 PM

Have you tried seeing if the issue happens by connecting straight to the modem?

What antivirus software, if any, are you running?

I haven't connected my computer directly into my modem yet. I'll try that. As for anti-virus software, aside from what I just installed to check if it was a malware issue, I haven't been running any.

This post has been edited by AspirantMage: 18 June 2011 - 11:32 PM

That does remove one possible cause from the list.