Are you running anything else on that PC that could make SQL server unresponsive?

>I have an ongoing problem that I have tried and tried to resolve.
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>A coworker and I are developing a VB 2008 desktop application using SQL Server 2008 Developer's Edition as a backend. When we install the finished application, it will use SQL Server 2008 Express locally on the same computer.
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>At the moment, we have SQL Server 2008 Dev Ed installed on an XP Pro workstation (which is not used for anything else) so we can both make changes to the database as we develop our application.
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>This normally works great, but intermittently - for no apparent reason - one of us (or the other, or both) cannot connect. We get the dreaded "a network related or instance specific error occurred while establishing a connection to sql server...." error. I have googled this and researched it and made sure all the standard causes of this error are addressed (firewalls turned off, allow remote connections turned on, TCP/IP turned on, network adapter drivers updated, etc, etc). And the thing is, the connection often works great! But several times a day, it just won't connect. And I may have connected just fine 2 minutes before. Then, ten minutes later, its all working again..... sometimes I restart and its back working.... sometimes my first attempt after rebooting fails.... sometimes disabling my network connection and then re-enabling it makes the problem go away.... sometimes this does not help. If I try and look at a shared folder on that PC with SQL Server when SQL Server refuses to allow a connection, there seems to be no problem (so its not like the workstation with SQL Server has disconnected from the network or gone into power save mode or something - its fine and I can still access its shared folder on the network). When SQL Server refuses to allow me to connect, it doesn't matter how I connect - either using our application or using SQL Server Management Studio - it just absolutely will not let me connect... then another time, it will, without a problem.... this makes no sense!!
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>Needless to say I just want to scream! Though thats not likely to help - it might make me feel better! ;o) This just seems so flaky... especially for a database Microsoft seems to really be pushing us all to use! There just does not seem to be any pattern to this connection issue.
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>Anyone else see this? Or anyone have a suggestion?