Thanx for Your advice - my mouse runs smoothly now
As about the damn module init tools: I fixed the problem

Kernel 2.4 and 2.6 runs without ANY errors now, this is what I did:
I uninstalled an rpm "modutils 2.4.22" from the system - this was very important! Then I installed newer "modutils 2.4.27" from an rpm, of course previously uninstalling any module-init-tools that ever existed. Having done so, I installed "module-init-tools-0.9.15 pre4" in the following way:
./configure --prefix=/
make moveold
make
make install
./generate_modprobe.conf /etc/modprobe.conf
depmod
depmod 2.6.4
And since than kernel 2.4 has been running perfectly. I partially got know how this module thing works - kernels 2.6.x use modprobe.conf instead of modules.conf file. "./generate_modprobe.conf /etc/modprobe.conf" converts options from modules.conf into modprobe.conf.
There's was however a problem with kernel 2.6 - when the init script starts, it shows errors (a few FAILED labels) referring to USB saying that it can't find any modules which handle e.g. usb-uhci, which is incorrect because I installed these modules when recompiling the 2.6.4 kernel. I got know that usb-uhci module has had their name changed in kernel 2.6 – I easily changed that in aliases in modprobe.conf.
There were also problems with keybdev and mousdev modules which wouldn’t like to load properly. Reading the Forum I encountered the following solution which happened to work:
/etc/rc.d/rc.sysinit @ line 207:
needusbstorage= <-- line 203
if [ $usb = "1" ]; then
needusbstorage=`LC_ALL=C grep -e "^I.*Cls=08" /proc/bus/usb/devices 2>/dev/null`
LC_ALL=C fgrep 'hid' /proc/bus/usb/drivers || action $"Initializing USB HID interface: " modprobe hid 2> /dev/null
if [ `uname -r | awk 'BEGIN {FS = "."};{print $2}'` -lt 6 ]; then
action $"Initializing USB keyboard: " modprobe keybdev 2> /dev/null
action $"Initializing USB mouse: " modprobe mousedev 2> /dev/null
fi
fi
Now everything goes well – the end of “module-init-tools” nightmare

Thanx again, Steve. CU online.