Mailpress problem

I’m trying to get Mailpress running. Managed to send out mail once but no more. I get the following errors when I run the test:

Warning: fopen(/www/business/5382/wp-content/plugins/mailpress/tmp/MP_Log_mailpress_MP_Mail_20090102.txt) [function.fopen]: failed to open stream: Permission denied in /www/business/5382/wp-content/plugins/mailpress/mp-includes/class/MP_Log.class.php on line 103

Warning: fputs(): supplied argument is not a valid stream resource in /www/business/5382/wp-content/plugins/mailpress/mp-includes/class/MP_Log.class.php on line 104

Warning: fclose(): supplied argument is not a valid stream resource in /www/business/5382/wp-content/plugins/mailpress/mp-includes/class/MP_Log.class.php on line 105

These are lines in question:

103 $this->fh = fopen($this->file , ‘a+’);
104 fputs($this->fh, $this->data);
105 fclose($this->fh);

Checked the permission on MP_Log.class.php and it was 644, changed it to 755 but no dif.

also tried configuring Mailpress to use POP instead of SMTP, no dif.

Any ideas?

Bill