Failure to deliver messages.

Hello everyone.

Lately when I chat with my girlfriend on Windows Live Messenger we don't get 80% of each others messages, and we don't get noticed about it. This brings us a lot of confusion (she thinks I don't reply at crucial moments etc. or don't care).

//Symptoms:
-80% of the messages don't get delivered, we don't get noticed, causing confusion.
-Her offline status appears on my side 10 to 20 minutes after she logged off, more confusion.
-It happens a lot when she's online, that it shows offline on my side (and no, this is not her blocking me or anything, we both know that), which makes her sad thinking I'm not replying to her (I am, but she's appearing offline). Then after she re-logs on, I can see her online status properly.
-I tried troubleshooting by telling her to go on IRC with me, but same symptom of not delivered messages, not warned. mIRC showed that she had constant Ping Timeouts.

-today I chat with my friend on Windows Live Messenger and I get the "2 messages not delivered - 1 delivered" symptom. At least this time it shows that the messages don't get delivered. But, still a problem. Had this problem before in the past.


//My Configuration
-I got a simple desktop firewall, McAfee 7 with latest updates
-Windows Firewall is Off
-Simple desktop PC with Ethernet NIC, and a T1 half duplex cable connection, Motorola modem
-ISP: telenet
-I have Hamachi installed recently (shows as seperate connection in "Network Connections" (Hamachi is a VPN tool))

//Her Configuration (which I think is the problem)
-xDSL modem and Ethernet NIC
-DHCP router (any PC/laptop can plugin and get directly internet)
-relatively new laptop (maybe with a WLAN connection inside)
-Desktop PC (she chats on her laptop though)
-She lives in a student buidling where they have "free shared internet",
which is probably one shared connection over the whole building (causing lag and timeouts?). Everyone is connected to each other (traffic overload -> packet loss?)

//Troubleshooting
-I tried mIRC with her, didn't help much
-Tried going from MSN Messenger 7.5 to 8.0 (Live)
-Could spyware malware be causing this problem? Already did a fresh updated scan on ad/spyware yesterday with Spybot and Adaware.
-Today someone told me he had the exact same syndrome at the exact same time (warnings about non-delivered msgs on msn messenger)


//What do I think?
-I think the warnings-part might be server sided (MSN servers?)
-I think the NON-warnings part is most probably her side, as she is getting timeouts (packet loss?)
-Most probably her side as she has a shared connection over many students in one building

What could I do to troubleshoot this?
It's really bringing us trouble..

Many thanks for your attention.
Any ideas are greatly appreciated.

Treval

p.s.: Strange..right now I'm getting "a network cable is unplugged" message..damn.."limited or no connectivity" message (MSN servers unstable or my ISP..? Perhaps IP renewing problem from my ISP's DNS server..don't know..) Great..I can't connect to anything anymore -copy pastes this and posts after reboot-