Recebemos uma resposta parcial (funcionalidade completa, ainda sem noção da causa da instabilidade) neste link: Post do fórum do Ars Technica
I'd suggest looking into this TechNet article. I came across it while trying to figure out why some of our domain logon scripts that worked under XP wouldn't work under Win7. I never actually implemented the suggested fix, because it turned out to be a better idea to get rid of the old, utterly pointless logon scripts, but it sounds like your situation may be similar enough that it could help you.
Basicamente eu apliquei a correção de registro referenciada, mudei o serviço crashplan para rodar sob minha conta de usuário "com as mais altas permissões", reiniciei e então consegui ver as unidades de rede sem causar instabilidade.
A chave de registro propriamente dita sugerida pelo artigo do TechNet mencionado é:
1.Click Start, type regedit in the Start programs and files box, and then press ENTER.
2.Locate and then right-click the registry subkey HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System.
3.Point to New, and then click DWORD Value.
4.Type EnableLinkedConnections, and then press ENTER.
5.Right-click EnableLinkedConnections, and then click Modify.
6.In the Value data box, type 1, and then click OK.
7.Exit Registry Editor, and then restart the computer.