Those are the two logs that have the information you need. You could try setting the log level to high, but it looks like you already have that set. You could also try to correlate events in the Windows event logs. This application is good for that: http://community.qlik.com/qlikviews/1029
You working set size is 90 - 98%. Why so high? Default is 70 - 90% I think. Based on the perf log it looks like you're getting close to that RAM limit. This shouldn't cause a server crash, but sometimes it does.
Did you really have no server traffic between 02:36:00 and 14:52:00? Or are those just snippets from the logs? Sometimes when the server crashes, it stops logging to the log file.