Try to upper the memory setting for PHP. See [url=http://manual.b2evolution.net/FAQ_:_After_Installation#When_I_do_xyz_I_just_get_a_blank_page_or_only_a_half_page]the Wiki[/url].

Good luck

I did that. My host says:
You can increase the memory size limit for php through the .htaccess file with the following command :
php_value memory_limit 50M
so I did that (adding this line to the .htaccess file in my roo tdirectory -> still no success, again empty page /htsrv/login.php

what else could it be?

Is the blog itself (without logging in) Ok or faulty also?
Try uploading the folders /inc/ and /skins_adm/ again. there may be a corrupt file in the server. This may have happened during the first upload.

Good luck

the blog iteslf is also faulty, empty page, no code at all in source, even after re-uploading the 2 folders you talked about. Shall I send you a PM so that you can check yourself?

ok

Update:
This problem was easily solved by upgrading to php5.