I have found that the default file manager for LXDE, pcmanfm, is not as "stable" for mounting network shares.
I suggest that you install and try nautilus as it is more functional and stable for mounting network shares. Plus, its list of dependencies are not nearly as long as dolphin. Dolphin would bring in a lot of KDE dependencies, whereas nautilus with its dependencies would not be nearly as large to download and install.
Plus, nautilus has several add-ons that make it even better so be sure to look these over and get what you need.
Desktop: AMD 3.6ghz X4, Gigabyte MB, 8GB ram, Multiple PCLOS's, 22.214.171.124-pclos3.pae.bfs
Server: Intel 3.4ghz X2, 4GB RAM, SATA, gnome2, *.pae.bfs, Headless, Servers: LAMP, FTP, Samba, Print, PXE, BT
HTPC: Phenom II X4 2.8ghz, 4GB Ram, 1TB SATA, PCLinuxOS-KDE, NVIDIA N220GT HDMI, *.pae.bfs