Server Memory Leaks

i'm running Suse 10 linux server in my company, and that server is used primary for graphing solutions, and data gathering.

server is fujitsu-siemens primergy rx100 s2 - suse was the only OS that detected disc controllers at that time.

It runs tons of queries to bunch of devices via SNMP and stores data in RRD files and some other data to mysql. It also runs a web server for displaying that data.

queries are short PHP script, that runs in CLI mode by cron

Few months ago my company switched to MPLS routing of our local network, and IMHO that was done very bat so sometimes i get timeouts, or networks run very slow.

other thing is that i server is behaving really weird.

Issue 1 - memory leaks or something like that
After restart it works quite fine for about 10-15 days, but after that when i run top i see that apache is using more and more VIRT memory, it starts with 8 megs per process and ends up with 150-200 megs per process.
things i tried to fix:
recompiled from scratch (php,mysql,httpd,snmp,maybee even libc but i'm not shure about that) all latest stable version, no improvements - when it runs it runs like hell, but after few days it starts to eat memory again.

Issue 2 - strange CPU load
after few days of flawless work, when it starts to eat memory it starts increase load, BUT in period of 08-20h load increases up to 100 and then suddenly drops to 1-2... and then in next morning it starts to rise again

only thing that comes to my mind is that ether:

- some computer is infected wit some virus, so in work hours it kills my machine - but ther is nothing weird in netstat

- doe tho lousy MPLS routing server is getting bunch of timeouts in work hours when we have large amounts of traffic, so the poll queue get larger and larger (cron runs every five minutes)

-everything is messed up - i need to reinstall everything (I'll rather shoot my self in the foot )

so what i'm asking here is HOW to gather data on what exactly is happening on that server, I'm quite experienced in writing shell scripts so it would not be a problem for me to write some custom scripts to analyze traffic, ports, (using iptraf) i just need someone to tell me WHAT and WHERE to look.

P.S. 1
Almost Everything on server is compiled by me, in order to get maximum from hardware. No RPM's

P.S. 2 PHP and Mysql are already well tuned and optimized - query cache works, APC is installed, for first 10 or so days it can handle A LOT of load without a problem.