first thing to do is to ask your hosting provider to set your site to use asp.net 1 instead of asp.net 2 DNN2 will run under asp.net2 but when they update the server to verson 2 they also change the permissions on the web site - this stops DNN2 in its tracks -

The hosting provider can access IIS and set your site to the correct asp.net version without any problems to them.

The errors you are getting can be linked to three areas

1) the connect string in web.config this applies to dnn2,dnn3and dnn4

2) the dll's in the Bin directory - files can be corrupted in the cache areas - simply delete all dll's then access the site then upload the dll's again. Usually fixes it

3) permissions. - can be two areas - one is the provider does not understand how to set permissions (was common in shared hosting) or updating the server software can change permissions.

Your problem is most likely to be (3)

There is also apparently a problem in the latest version of Hsphere ( which is really a beta) with asp.net site configuaration - If your control panel is Hsphere and it is version 3 which form memory version2.5beta then there could be a problem however I think it is more likely that it is the problem above.

If your hosting provider has your site set to use asp.net 1 already then email me privately and I shall give you a patched version to overcome the problem where the provider is not setting the permissions correctly on shared hosting.

I think the main restriction in moving to DNN3 or DNN4 for this person is the fact that he needs to use MSaccess database - Version3 and 4 do not have providers for MSaccess - so his choices are quite limited.

However even if you are using sql one does not need to move to V3/4 unless you need the membership functions or localisation - (localisation is available for DNN2 via addon module). There are sone changes in the GUI with v3/4  but they are not life changing. If you just want to run a website then V2 is still the most stable way to do it and it does have I think the most free and open source addons of all the versions. If you also just want to learn asp.net and the inner workings of DNN then version2 also gives I think the best platform for doing that

If you want to cut your teeth on DotNetNuke then starting with V2 is a good way to go  - you may run into istallation problems ,permission problems etc as you would with V3/4 but basically they will be the only problems - the code is highly stable - once you know dnn then if you need the extra functions in V3/4 then update . Don't chase versions just for the fun of the chase

DNN2 does not need the first connection string set - it is used by some early modules to update, not by the framework.

Basically you should leave the web.config file exactly as it comes if you are using MSAccess - dnn2 defaults to MSAccess. You can check this by looking at the statement

 <data defaultProvider="AccessDataProvider" >

If you made any changes to web.config then simply upload the orginal one.

Your hosting provider does have both asp.net1 and asp.net2 - it is important that they configure your site to use only asp.net1 they do this in IIS (5 minute job)

Any way I have sent you an email with the link to get the patched version to give it a try. Generally now adays dnn2 should run on any shared hosting environment but there may be still some who do not configure the permissions correctly - if this is the case with yours then the patch will fix it.