BV Subscript out of range, network issue?

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Hello,

We are using BV version 7.53 on Windows 7 64 bit PCs and have been getting some random errors.  This particular one occurred when entering an invoice in the accounts payable module.  Server is running 2008 R2.  Our support team is indicating that this might be a network related issue.  Server is running 1GB Ethernet to the HP Procurve switch with no known issues of performance. 

The specific error: 

Just need a second opinion as I don't understand this error at all.  Is it / could it be caused by the network? 

Thanks 

Peter