Network not being recognized

I have a Dell Inspiron580 and a Dell Studio 17 laptop. Yesterday they recognized each other. Today the laptop can access the desktop but the Desktop does not recognize the laptop. I thought it was a Linksys problem but they told me it was computer related. The laptop could ping the desktop but not viceversa. At one point, while talking to the Linksys tech, the name of the laptop showed up under Network but when I clicked it it could not be found. it was suggested that it might be related to a firewall but I don't see how that could have changed since yesterday. Any suggestions would be appreciated

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz, Intel64 Family 6 Model 37 Stepping 5
Processor Count: 4
RAM: 8055 Mb
Graphics Card: ATI Radeon HD 5450, 1024 Mb
Hard Drives: C: Total - 939685 MB, Free - 818910 MB;
Motherboard: Dell Inc., 0C2KJT
Antivirus: Norton Security Suite, Updated and Enabled