@basarovski
probably you installed some buggy package from extras-devel, try to uninstall it in hope it have files backuped / files are able to reinstall.

make sure to NOT use baterrypatch and speedpatch. speedpatch just destroy nokia settings about software priority (sometimes it help but mostly harm). baterrypatch just swaps between two profiles and do several random things. not only it would interfere with kernel-config, but also it's incompatible with KP49 since it's default and sample profiles are much adjusted, both to have better batterry performance and it's crucial because of recent changes in kernel

@pali
recently (about a week ago) i updated KP49 beta to KP49 from extras devel. it seems to work stable, but i noticed i still have bugs related to usb networking, which may lead to reboot. also i confirm the reboot is broken still. /sbin/reboot want's to just shutdown, also when rebooting it may fail generallly or just make after-boot process crash.

I'm not complaining, just confirm the old bugs. to help diagnose them i'd share some info:
- i have busybox-power and multiboot and CSSU installed
- from behavior of multiboot while run after reboot i notice that those problems occur on different stages
- when in boot into menu after reboot from KP49 and choosen another kernel (eg. nokia stock one) the kernel could also fail (confirmed)
- when rebooted from another kernel (eg. nitdroid one) and booted into KP49 the kernel could also fail (confirmed)
- it may fail to load multiboot menu sometimes (confirmed)
- I managed to usb networking (where PC is router and PC and N900 are linked by usb cable) be able to run on stock kernel, and it occured that USB-networking-bug happenned at least once (it was the bug not plain incompability since i was able to transfer some data)
- the one above suggests it's a bug in driver, so it's not mainly related to the kernel power, but it may be a bug in driver firing a bug in KP (we had some once, and i believe it shouldn't crash the system, just break connection)

@people having problem with upgrading from KP49 beta to KP49 final
i noticed that fappman (and also probably stock application manager) don't show the option to upgrade because it thinks it's the same version.
I managed to upgrade using apt-get from commandline. I believe i used just upgrade command, but if i don't remember properly I may used install --reinstall. it has done peacefully.

@asking for help
I have the bootimg and modules from KP 48 still installed, and I'm shrinked of rootfs, even though i optified some non-crucial software by hand (and I hate maemo-browser libdir for having relative symlinks so it don't work by just moving whole directory and symlink the directory - it needed more work to be able to work).
I'm a compulsive installer wanting have all useful stuff, but you cannot enlarge rootfs, and also i don't believe KP 48 is anything better than KP 49. SO I WANT UNINSTALL KP48 AND STILL KEEP KP49. sorry for too much chattering.

EDIT: recently i installed both newest KP49 and newest CSSU and found that the startup lag (after the boot, before GUI fully loaded) decrased noticely. It may be just CSSU fixed old nokia bug, but perhaps having recent KP49 help. I feel fine with my phone and geeked it much, but i still haven't used the overclock, but i probably will once warranty voids because of time (when i would overclock it theoretically void instantly, and I bought an used N900 one so I don't want to it make itself broken because of something wrong i wan't told during the but process and have no warranty)