MacBook looses WIFI and freezes frequently

Hello there!

Since a few days, my MacBookPro Mid 2009 frequently looses the WIFI connection and freezes (not both at the same time).

Both problems started to occur at about the same time, so I think there may be a connection.

The WIFI just looses connection from time to time. The WIFI symbol in the menubar stays on "connected", but when I click on the menubar icon, it doesn't show any networks and isn't connected to anyone, although the icon stays as already mentioned in the "connected" state. Turning off the WIFI from within the menubar changes to the menubar icon to the "off" state. Turning it back on again doesn't work and in the system settings it says that my WIFI is still on. The only way to get it working again is rebooting.

I guess that the freezing occurs less often than the WIFI loss. When my MacBook freezes, it freezes completely. I can't move the mouse anymore and can't change anything with the function keys (e.g. display brightness). The only way to turn it off is holding the power button for a few seconds.

I first tried reseting the DHCP-Lease, SMC and PRAM. I also checked the access rights and my SSD using the Disk Utility. My SSD seemed to be okay and the disconnects and freezes still occurred (The Disk Utility isn't able to repair to repair the file "Applications/Safari.app/Contents/Resources/Safari.help/Contents/Resources/inde x.html" but that doesn't seem to be a problem, right?).

I also did the basic Apple Hardware Test, no problems were found.

After restarting my Mac after another freeze, my WIFI hardware wasn't recognized anymore (cross in the menubar icon). I did the basic Hardware Test again and it still didn't find any problems. I also think my Airport Card wasn't recognized in the Mavericks System Report and the Hardware Test, but I'm not a pro, so doubts on that.

I then decide to repair my system installation because the WIFI still worked in the Recovery Partition.

After reinstalling the OS (without deleting all my personal files and apps) the WIFI worked again, but my Mac still froze and lost connection frequently.

A few hours ago I rebooted after a WIFI connection loss and my Mac instantly froze when it finished booting up.

Just about one hour ago this happened again.

I'm out of solutions now and can't find help using google. There aren't any Apple stores near my location and I also can't give away my Mac in the next few weeks. It's currently essential in my daily work and those freezes make working with it very difficult. Just buying a new one isn't a possible solution too.

I'm using 10.9.2 and didn't change anything recently. No system changing apps or anything like that and no hardware changes in the last few months.

I replaced the cd drive with a Samsung SSD a few months ago (I enabled TRIM with "Trim Enabler" by Cindori Software just yesterday) and migrated my data to the SSD. The original hard-drive is still in its place, but almost empty. I also upgraded the RAM to 8GB, but the problems still occurred when I changed it back to the original 4GB. My fan works fine and all the wires are in place. Here's an link to the system logs from a few minutes before the last freeze. I uploaded it to my webspace, because I don't want to fill the whole threat with it, hope thats fine.

Thanks in advance to anyone out there who's willing to help,

I really appreciate your work on the forums.