Good to hear its working again... I would assume that you may have an intermittent connection issue if the systems were rebooted both multiple times with no link. If this happens again, I would swap out the Cat5 cable.
Kind of curious though as to how you are making this work without a cross over cable if these systems are both not connected to a network switch or hub to perform the cross over connectivity. I have yet to see the ability to connect two systems together with just a regular patch cable as for the problem is that the TX and RX are mismatched using a regular patch cable and I am not aware of any network adapters that have internal switching to bring PC1-TX to PC2-RX and PC2-TX to PC1-RX to allow for network communications.
Cross Over Cable Allows the following communications without a switch or hub as wired:
TX = Transmit
RX = Receive
PC1 PC2
TX --> RX
RX <-- TX
*Note: Both Talk and Listen to each other = GOOD
Here is the problem with 2 computers just using a straight-thru patch cable without a cross over ability:
TX = Transmit
RX = Receive
PC1 PC2
TX -->X<-- TX = Both Talking
RX --------- RX = Nothing Heard
*Note: Both are Talking but none are able to Listen to what is communicated. BAD = No Network Connection
These days switches are used with auto-cross over ability and so you have lots of patch cables and few cross overs used.
PC1 SWITCH PC2
TX --> INPUT <-- TX
RX <-- OUTPUT --> RX
*Note: Both PC1 and PC2 are using regular straight thru patch cables and the switch is performing the communications cross over. Also the switch allows for as many systems/devices ( aka nodes ) connected to it as ports are availble. So a 8 -port switch supports 8 nodes to interconnect.