Pls help me, can not install any application on my droid.



I am using a Samsung Galaxy 3 with android 2.2 and I want to install some application what is downloadad from many different sources.
I have red many questions about this issue but could not find a solution to solve it.
So now here is my problem:

1. I copy the choosen .apk file on my SD card.
2. I have downloaded ASTRO file manager.
3. I have ticked the option installing non-android applications.
4. I want to open the apk file from there but when I click on app installer I onyle get a blank screen and under the details I receive the following error message:

Could not open xy.apk as APK file.

I am really going mad now I have reading forums for ages.:mad::mad::mad:

Please help!!!



Thread starter
I have already tried that one as well as many other apk installers... However in the mean time I found out that there might be more serious problems here...

I have copied some music on my phone but after trying to playing them the media player says that the file format is not supported... They are just plain MP3 files nothing special...

What is going on???
Why does not my phone recognize file formats?