I noticed lately that I couldn't install a program from a website (not even from maemo.org). After few days i tried to do it from app manager but when turning it on and clicked download it couldn't find anything! Then I thought maybe I should delete my Pidgin messenger since it didn't work either anymore. Went to delete the programs from app manager and again it showed that no applications were installed.

I have a bad feeling this is because of the latest firmware update. Also some other not so normal things have happened after updating.

I saw in one thread that I should try to clean ( i don't know what, i'm not a pro user) via x-terminal by typing apt-get clean but i receive error messages like this:

E: Could not open lock file /var/cache/apt/archives/lock - open (13 Permission denied)
E: Unable to lock the donwload directory

If anyone has any ideas about fixing the problem i would be more than pleased to hear them. Thanks.

P.S. I am using a finnish version so i don't know the real english names for all the "buttons" in app manager.

Have you played with X Terminal as root? That could have somehow made some of your files root-only.

EDIT: And is your App Manager giving you the same permission denied error (look what it reads in the log).

The 13 permission denied is cause you're not root... Hope you have downloaded rootsh before this, if yes just type:
sudo gainroot <enter>
apt-get clean <enter>
If not you can't get rooted...

I have that problem to sometime that the app manager doesn't detect any apps. I just have to close it and the wifi (if on) and then turn on wifi and open app mngr

It might be that you're using to much rootfs space on your device. Do you have conky installed, if yes check the rootfs usage

If you don't have conky try this in xterm:
df -h <enter>
It will show the disk usage. The rootfs is in the top...

What does playing x-terminal as root mean? Haven't played in X-terminal basically at all so all the instructions could be nice to have in step by step

Edit: How do i check the log?

I think i haven't downloaded rootsh? Is my N900 doomed to be like this forever or is there something i could still do?

I don't have conky installed either I believe. At least I haven't done that. I checked the disk usage as you instructed and it showed 62 % for rootfs. Is it too much? Something I could do to to reduce it?

Application Manager -> Menu bar.

You can try to reboot the phone.

The rootfs looks just fine, lots of space no need to to make more space

You can't do any apt-get commands without being root...

Conky is a good safe app/tool to install, very usefull, shows your current state of phone, cpu - memory - rootfs - wifi and stuff like that

I'm not sure why you have problems, but it's not rootfs related and you havn't played around xterm...

In this case maybe a reboot would do you good if you havn't tried it yet?

I would try to open app manager from xterm, i just don't know the code to do it, sorry, i've looked for but couldn't find it...

If you want to be sure if you can get root just type sudo gainroot in xterm and you will know if you installed rootsh

I checked the log and it repeats three errors which are:

E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/downloads.maemo.nokia.com_fremantle_ssu_mr0_._Pack ages
E:The package lists or status file could not be parsed or opened.

Tried the "sudo gainroot" and follows with a message: "Enable RD mode if you want to break your device" so looks like I don't have it

I've rebooted (restarted) the phone for a couple of times but still having the same problem.. Any idea if this is related to PR 1.2?

http://wiki.maemo.org/Root

Did you try to reflash the catalogs (app manager -> menu bar).
If you did and it didn't help, try to disable nokia related catalogues (app manager --> menu bar )

I'd suggest going into App Manager and disabling all the repositories. Exit App Manager, then restart it and re-enable the repositories. That'll force a complete refresh of the repository metadata, which fixes a lot of these sort of issues.