error 500 with blank error parameters

We just recently migrated from IIS6 to IIS7 (both on different servers).

Our sites are based on asp classic. We designed it to email us if there are any issues with the serving of the pages.

One thing we have noticed during our migration is that we started to get error500 emails whose error parameters are blanks (see sample below). We know there is a problem but we cannnot pinpoint what is the issue. No make matters worse, this does not happen very often and we don't have a way to reproduce it.

A little background regarding our IIS servers. We have 6 web servers on a shared config and shared content environment under a haproxy load balancer.

Let me know if anyone has any ideas whay may be causing this. Thanks!

Contenu du QueryString :

aspxerrorpath=%2Fblogs%2Fp%

• 2Floupe%2Ffiche%2Easpx

  Caractéristiques de l'erreur :

  Propriété	Erreur
  ASPCode
  Number	0
  Source
  Category
  File
  Line	0
  Column	1950507110
  Description
  ASPDescription

  Gbook = 2/25/2013
  utilisateur = enreg_email_article
  ASP.NET_SessionId = g2ymc0sfsrdbydr13prxgt5w
  PHPSESSID = UBgBecHiMh1RjDmxtFQS20
  Nop.customer = 60ab9a0a-7f39-47f9-a236-be088a36a99a
  grossesse = sid
  product = ans
  slimdata = sid
  montignac = sid
  aujourdhui = pseudo
  chronodetox = sid
  naturelles = sid
  pendu = strLetters
  produit = validcodepromopartner