.NET objects hosted in IE works unstable

[smolotkov]

There is a web-application, a part of which uses .NET objects on client
side (embedded into HTML). There are about 100 thousand users. Users
have IE6 and .NET framework 1.1 or 2.0. Assemblies loaded to client
side are built under .NET framework 1.1, signed and have the attribute
AllowPartiallyTrustedCallers. Runtime Security Policy on client
workstation has default settings.

The problem is that the application works unstable: about 5-10% of
users have occasional problems:
· Application works without faults, but when closing IE an error
occurs.
· IE crashes at the first attempt of opening page containing .NET
objects.
or
· IE crashes while working with such pages.

Crashing of IE can look different. It can close quietly or can say
about an error and suggest sending a report to Microsoft.

Any help will be appreciated!