[BUG] Claude Desktop hangs and shows white screen on startup when mapped network drives (VPN) are unreachable

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

Claude Desktop hangs on startup (no response) and eventually shows a white screen when mapped network drives (in my case W: and X:, mapped over VPN) are slow or unreachable. This appears to happen because the app's Cowork VM tries to mount all local/mapped drives on startup — similar mechanism to issue #44486, which covers unreachable USB drives causing an immediate crash. In my case it's network drives causing a hang instead of a crash.

### What Should Happen?

The app should not block its main UI on mounting drives that are slow or unreachable. Inaccessible or slow drives (network or otherwise) should be skipped with a warning/timeout, not allowed to hang the whole app.

### Error Messages/Logs

```shell

```

### Steps to Reproduce

1. Map one or more network drives via VPN (e.g. net use W: \\\).
2. Disconnect the VPN, or otherwise make the mapped drive unreachable, while the drive letter is still mapped.
3. Start Claude Desktop.
4. The app hangs (no response) and eventually shows a white screen.

Workaround that resolved it: fully quit Claude Desktop (via system tray, not just closing the window), run `net use W: /delete` and `net use X: /delete` to remove the unreachable mapped drives, then restart the app.

### Claude Model

Not sure / Multiple models

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

Unknown exact version

### Claude Code Version

2.110.1

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

PowerShell

### Additional Information

Likely related to #44486 (CoworkVMService crashes when a drive can't be mounted as a Plan9 share) — same suspected root cause (mounting all local/mapped drives on startup), but manifesting as a hang/white-screen instead of an immediate crash, specifically for mapped network drives that are slow to time out rather than immediately erroring. Should not require the user to manually disconnect network drives as a workaround.

Extra info:
Claude Model
N/A — this is a Claude Desktop app startup/infrastructure bug, not model-specific

Is this a regression?
Possibly — seems related to a change where the app started mounting all local/mapped drives (same root cause suspected as #44486), which didn't hang before that change

Last Working Version
Unknown exact version

Claude Code Version
2.110.1

Platform
Claude Desktop app (subscription).

Operating System
Windows 10 Pro, build 10.0.19045

Terminal/Shell
N/A — Claude Desktop GUI

Start by tracing Claude Desktop startup into the Cowork VM service and the code that mounts local or mapped drives on Windows. Reproduce the hang with an unreachable mapped drive such as W: or X: and compare it with related issue #44486. Done means startup remains responsive, unreachable drives are skipped with a warning or timeout, and reachable drives still mount.

Written by the indexing model from the issue text.