WordPress.org

We have constant 500 server error and 401 Error.

Environment:

Word press, latest updates installed.

DreamHost was chosen as number 2 recommended hoster by WP.

Currently we use 17 plugins and custom-made theme:

Advertising Manager
Blubrry PowerPress
Contact Form 7
Facebook Comments
Global Translator
Google +1
PHP Speedy WP
Performance Optimization: Order Styles and Javascrip
Poll Lite
Really Simple CAPTCHA
Sociable RE
TPC! Memory Usage
Twitter for WordPress
W3 Total Cache
WP-DBManager
WP-Memory-Usage
WP Facebook Like

Here is our Memory report:

Usage Sample: 53.45MB (21%)
Peak Usage: 53.56MB (21%)
All-Time: 71.41MB on 7/13/11 @ 7:12 am (shutdown)
Load Averages: 0.9 0.95 0.88
WP Memory Limit: 1024M
PHP Memory Limit: 90M

DreamHost gives us undisclosed amount of memory on shared hosting and we are hitting 500 server error and 401 Error.

We did most of optimization recommended by DH. Nothing helps.
DH pushed for VPS. We do not have money to do it.

Our developers blame everything on WordPress where "all plugins are conflicting" and recommend to move to paid CMS or Drupal, at least.

Any suggestions? Maybe someone would recommend hosting company where allocated memory "is disclosed"?

Again, at least at this time we are not moving to VPS or dedicated hosting because we are not making any $$ from the website...